End of the trilobites

Adventures on Earth column for the Dec. 29 edition of The Review
By George E. Beetham Jr.
Two hundred-fifty million years ago, all of the Earth’s continents had come together in the supercontinent that geologists call Pangea.
The dynamics of plate tectonics are such that supercontinents do not last very long in geologic time. For one thing, the weight of so much continental rock pushes down on the mantle below, altering the convection currents in the viscous mantle.
Hot spots form under the supercontinent, getting larger and hotter until the magma pushes up to the surface. This begins the rifting process that splits supercontinents apart.
Pangea 250 million years ago was a continuous landmass stretching nearly from pole to pole. A shallow, continental sea had formed on the western side of the northern part of Pangea.
Over time this shallow sea formed bogs. Peat and vegetation built up and were buried, forming a vast coalfield. Although this area was a sea, it was over a continental shelf and thus part of the supercontinent.
A plume of hot mantle formed under that shallow sea, sending hot magma toward the surface. When it broke through, massive amounts of magma welled up and out over the surface.
The eruption triggered a chain of events that was to have a profound impact for life that existed at that time.
The eruptions continued for a million years, the lava spreading across an area estimated at seven million square kilometers.
In addition to lava, the volcanic vents spewed out gases – carbon dioxide, methane, sulfur aerosols, and water vapor. Ash was also expelled.
The particulates and gases spread into the atmosphere, circling the globe. The gases are prime greenhouse gases trapping heat below and the particulates blocked sunlight from above.
The magma rose through the coal beds, igniting the coal and adding to the environmental disaster that was playing out.
All of this, again, played out for a million years, altering weather as well as the atmosphere.
It was at that very time, 250 million years ago, that the largest mass extinction in the history of Earth took place. An estimated 90 percent of species that existed prior to the eruptions went extinct.
It marked the end of the trilobites, crustaceans that plied the sea floors. Trilobites had existed since the Cambrian and were once plentiful in the seas of the planet. They survived mass extinctions time and time again. Although some members of the clan did go extinct in these earlier events, trilobites as a whole continued on, adapting to changing conditions.
By the Permian, only one species of trilobites was left, but that expired when the Siberian traps erupted.
Included in the extinction were marine creatures and land dwellers. No part of the biosphere was spared.
Yet some creatures did survive into the Triassic Period that followed the Permian.
These survivors adapted to the conditions that prevailed, branching out to form new species.
It took an estimated 30 million years for the planet to totally recover from this catastrophe, but the Permian mass extinction did accomplish one significant thing.
The turnover in fauna greased the skids for the rise of dinosaurs and other species that sprang from the survivors.
As dire as the disaster was, it brought the world closer to being inhabited by humans. Another disaster 65 million years ago brought it further along.
Every great dying in Earth’s history has been followed by a period of recovery, and then species radiate out to fill ecological niches once occupied by the now deceased creatures.

Monster Storm Could Finish as Christmas Weekend New England Blizzard

State College, Pa. -- 23 December 2010 -- AccuWeather.com reports the caboose in the series of storms walloping California and the Southwest with flooding rain and yards of snow will bring a white Christmas to parts of the South, a coastal mid-Atlantic snowstorm Sunday and perhaps a New England blizzard on Monday.
Stop playing with your snow globes and grab the snow shovels, as the former monster West Coast storm will spread snow cross-country to the East Coast over the long Christmas weekend.
The storm will bring a moderate to heavy snowfall over parts of the Plains. Enough snow will fall in part of this area to disrupt travel and cause shovels and plows to be needed over a large part from the I-70 to I-90 corridor. Omaha, Huron, Des Moines and St. Louis, that's you!
An energy transfer toward the south will cause snow to become spotty and light over the Ohio Valley region. Even so, pockets of slippery travel can be expected from the I-40 to I-80 corridor with snowfall ranging from a few flakes to a few inches. The snow will cover Chicago, Louisville, Cincinnati and Nashville.
In the South, essentially from the I-20 corridor northward to I-81, it seems a white Christmas is in order, but also travel problems due to road conditions ranging from wet to slushy to icy and snow covered.
Snow accumulations will range upward from a coating to an inch or two in portions of northern Alabama to several inches over northern Georgia to western North Carolina to perhaps a half a foot or more in southeastern Virginia and part of northeastern North Carolina.
The storm will continue to grow in size and strength along the mid-Atlantic and New England coasts, but the storm track will hold the key as to how severe the storm is and how much, if any snow falls on coastal to inland locations.
AccuWeather.com meteorologists want to stress that a shift in storm track as little as 50 miles could mean the difference between flurries or a nuisance snowfall and a back-breaking snowstorm or blizzard.
In this case, the farther east you are, the worst conditions would be. This applies particularly from Washington, D.C., to Philadelphia and New York City on Sunday.
It seems an all-out blizzard will unfold Sunday night and Monday at least part of New England.
Most of our forecast tools and opinions of meteorologists at AccuWeather.com are in agreement for wind-whipped snow for eastern New England with the storm. Again, depending on track, parts of New England could be in line for a foot or more of snow.
A track closer to the coast could not only bury the I-95 mid-Atlantic cities, but it could also bring rain to Cape Cod.
As a result, people may have problems getting home from holiday ventures early next week as a result, especially in the coastal mid-Atlantic and New England. Conditions will be cold, but improving in the South by that time.
AccuWeather.com meteorologists will be working around the clock through the Christmas weekend providing up-to-date weather information.

PennDOT Urges Holiday Travelers to Monitor Forecast, Avoid Travel if Winter Storm Strikes this Weekend

Harrisburg – With weather forecasting models offering uncertain outcomes for Christmas weekend, PennDOT is urging motorists to closely monitor forecasts and make smart decisions before deciding to travel.
“Anyone with travel plans should be aware that there is the potential for a major winter storm that could have a significant impact on all or parts of Pennsylvania this weekend,” said PennDOT Secretary Allen D. Biehler, P.E. “It’s essential for motorists to carefully monitor weather forecasts and check conditions along their entire route before traveling this weekend.
“If a winter storm does strike, our advice is to avoid traveling unless absolutely necessary – for your own safety. If you must travel, use common sense, pack an emergency kit, have realistic expectations of road conditions and remember that if winter precipitation is falling, roads will not be completely free of ice and snow.”
Although PennDOT crews will be plowing and treating roadways around the clock as necessary, the department’s primary goal is to keep roads passable, not completely free of ice and snow. PennDOT will continue to treat roadways throughout the storm until precipitation stops and roads are clear.
Motorists should remember that interstates and other high-volume expressways are treated first during winter storms. Secondary state routes are a lower priority and during severe winter storms, deeper accumulations will occur on these roadways.
“The easiest way for motorists to avoid having a crash or getting or stranded is to stay off the roads when common sense dictates that you should,” Biehler said. “Remember: we can’t plow it if you’re stuck in it.”
Although PennDOT recommends not traveling during winter storms, motorists can check road conditions on more than 2,900 miles of state roads by calling 511 or visiting www.511PA.com. 511PA, which is free and available 24 hours a day, provides traffic delay warnings, weather forecasts, average traffic speeds on urban interstates and access to more than 500 traffic cameras. The 511 site also provides easy-to-use, color-coded winter road conditions for all interstates and other routes covered in the 511 reporting network. Regional Twitter alerts are also available on the 511PA website.
The department also asks motorists to allow plenty of space when driving near plow trucks. Also, for their own safety and the safety of plow operators, motorists should never attempt to pass a truck while it is plowing or spreading winter materials.
PennDOT reminds motorists to pack an emergency kit for their vehicles. A basic kit should include non-perishable food, water, blanket, small shovel and warm clothes. When preparing an emergency kit, motorists should take into account special needs of passengers such as baby food, pet supplies or medications and pack accordingly.
For more winter driving tips and information on how PennDOT treats winter storms, visit www.dot.state.pa.us/winter.

Gold was airmailed to Earth

Adventures on Earth column for the December 22 edition of The Review
By George E. Beetham Jr.
Gold is one of the most fascinating minerals on Planet Earth, but the gold we mine was not here when the planet formed.
A study recently published in the research journal Science claims that the gold we find on Earth probably came from the crash of a large body, perhaps even a small planet, with Earth long after it formed.
Gold is often found in conjunction with iron. The Earth’s core is made of iron. All the gold that may have formed as the planet organized would have sunk into the core along with the iron.
But gold arriving via a crashing body from space would not necessarily have settled into the core. Assuming the body from space was large enough to bring a lot of gold to the planet, it could not have been so large that it would have melted down to the core.
Instead the gold that piggybacked its way here settled into the mantle, the region of viscous rock that churns and drives the continents around the planet.
Gold is found at the surface in conjunction with rocks formed of magma or rocks that have metamorphosed.
Gold can be expelled from volcanic vents, or it can be carried by liquid water that eventually forms quartz.
By far, the most common form of gold is found in veins of quartz. When the quartz fractures apart and weathers away gold nuggets and flakes are washed into stream where it can be panned or extracted by hydraulic or mechanical means.
But large mining companies tunnel into quartz veins, breaking up the rock. The ore is processed to extract the gold.
The Earth is estimated to be about 4.5 billion years old. Any gold that came to Earth during that time would have settled into the core.
Researchers estimate that the gold that formed in the mantle came from the collision with a large space rock tens of millions of years later.
Otherwise, we would not have been able to find gold at the surface, or in rocks reachable by mining. It is estimated that we have recovered some 165,000 tons of gold.
Gold is prized for its beauty, but it has a practical property as well. Gold does not oxidize, or corrode. It does not react to acid, which provides the standard test geologist use to prove it is gold.
Gold is valued in jewelry, coinage, and industrial uses. Gold is used in electronics, medicine, and chemistry.
Despite the fact that it does not react to the body, gold flakes have been used in drinks and gourmet foods. Although some people historically thought gold was good for humans, it has no nutritional value and passes through the system without any effect.
Gold remains a measure of wealth and in recent years people have been investing in gold, driving up the price.
Gold in its own right is fascinating, but the way it arrived on the planet makes it even more fascinating.
To paraphrase Mark Twain, buy gold; they’re not making any more. What we have is all we’ll get, unless another large body gets air mailed from space. That would bring more gold, but likely wipe out the creatures that value it.

A battle over geology

By George E. Beetham Jr.
Adventures on Earth column for the December 15, 2010, edition of The Review
The Battle of Gettysburg was among the most studied events of the American Civil War, and what few people realize is that geology played a very important part. In fact, geology was a major factor in the entire campaign leading up to the battle and following the battle.
When Confederate Gen. Robert E. Lee decided to take the war into Pennsylvania that summer of 1863, the first thing he had to do was plan how to get his Army of Northern Virginia on the move toward the Keystone State and avoid the Federal Army of the Potomac, then commanded by Maj. Gen. Joseph Hooker.
Lee decided to move his army into the Shenandoah Valley, away from Culpeper, Va., where the two armies had faced one another following the Battle of Chancellorsville earlier in the year.
Lee moved his army to Sperryville in the eastern shadow of the Blue Ridge, crossing the Blue Ridge into the Valley near Front Royal.
The Blue Ridge is made up of metamorphic rocks of volcanic origin, an old island arc that became part of North America just prior to colliding with Europe and Africa to form the ancient supercontinent, Pangea.
The rocks of the Blue Ridge include some granite, Catoctin greenstone (a metamorphosed lava), and an outlying ridge composed largely of Cambrian quartzite. All of these rocks are very hard and resistant to erosion, which is why they form ridges.
Once in the Shenandoah Valley, Lee sent cavalry to control the gaps that the Federals might have sent to locate him. Thus obscured from the prying eyes of the Federals, Lee moved north into Pennsylvania.
From Chambersburg, located in the Cumberland Valley of Pennsylvania (both valleys are part of the Great Valley that runs along the Appalachians), Lee sent one division north and east toward Harrisburg. He sent another element east across South Mountain toward York and the Susquehanna River.
Meanwhile, Lincoln replaced Hooker with Maj. Gen. George G. Meade. Meade hurried his army northward to locate Lee.
The town of Gettysburg was the hub of roads that radiated in all directions of the compass. It was there that Federal Cavalry located Lee and began the battle.
On the first day, July 1, 1863, the two armies formed along north-south ridges west of town. Holding the high ground was a defensive move, allowing an army to fire down on attackers.
As more units arrived, the battle lines stretched around the north side of the town. By evening, the Confederates had pushed the Federals south of town, where they took up positions along Cemetery Ridge and Culp’s Hill.
The battle line resembled an inverted fish hook, leaving the Federals in control of roads leading to Baltimore and Washington.
It was along these lines that the battle played out on the second and third days.
Gettysburg is located in what is known as the Triassic Basin. No longer a basin, the geologic formation was formed as sediments washed into an old rift valley that formed as Pangea began to break apart.
The red shales and sandstones of the basin hardened and fractured. In time an upwelling of magma extruded up along the fractures in the rock, forming a hard, resistant rock known as diabase.
As the softer red shale and sandstone eroded, it left the diabase beds as ridges. All of the ridges around Gettysburg were formed this way. The Federals occupied the higher of the ridges, dominating the area from Cemetery Ridge on the Federal line to Seminary Ridge on the Confederate line.
After the battle, Lee withdrew his wagon trains through gaps in South Mountain, screening the Army of the Potomac to the east.
While geology was a factor in the campaign, it was by no means decisive. But the Federals did make good use of the terrain they found, and that made all the difference.

The first Americans

By George E. Beetham Jr.
Adventures on Earth column for December 8, 2010, edition of The Review
A cliff in eastern France looms over a rural valley. Sand dunes in southern Virginia lie within a loop of the Nottaway River.
Though geologically different, the two sites may be linked together to tell the story of the first inhabitants of North America.
The Rock of Solutre is a limestone mesa whose flanks are covered with vineyards. The rock dominates the region where artifacts of people who lived between 22,000 and 17,000 years ago were found.
These people subsisted on reindeer in a time when the last glaciation extended southward into France.
They left artifacts in caves in the region – stone and bone tools that had a distinctive kind of flaking. Also in the caves were drawings of animals of their world.
Named the Solutreans for the site where these artifacts were first found, these people lived in a wide area of southern France and Spain.
Cactus Hill is a tree-covered, 75-foot dune inside a loop of the Nottaway River. It is the location of an archeological site where two cultures have been found.
The most shallow was the Clovis culture. A deeper level contains artifacts from people who lived earlier than the Clovis – some15,000 to 18,000 years ago.
Both the Clovis culture and the earlier culture left stone tools that have the same flaking method as the Solutrean people of France. Bone tools like needles used to sew hides into garments and other implements also mirror Solutrean culture.
This discovery has completely unsettled what had been a prevailing theory about the origins of humans in North America.
The first Clovis site was found near and named for Clovis, New Mexico. Clovis artifacts have since been found in other sites, including Meadowcroft Rockshelter in southwestern Pennsylvania.
The old paradigm had the Clovis People moving into North America via the Bering land bridge that existed during the last glaciation, which ended some 11,000 years ago.
Since that theory first surfaced, archeologists have searched Alaska and Canada for artifacts of the Clovis People. They found none along the route that people moving from Asia traveled as they made their way into North America.
What is more, a skull of a person believed to have been Caucasian was found in a Clovis site in Washington state. Dubbed Kennewick Man, the skull was narrow rather than the broad skull of Asian migrants.
While Asians did migrate across the Bering land bridge, Clovis People may have come from France or Spain and entered North America long before Asians.
The Solutrean theory holds that Solutreans traveled across the Atlantic in small boats, possibly following the ice margin where seals and walruses would have provided food.
Theorists of this scenario point to similarities in the tools, evidence that is hard to dispute. There are others who argue otherwise, pointing to two distinct issues.
First, they say, the Solutreans show no evidence of sea faring skills. Additionally, the voyage across the Atlantic would have been too hazardous for any boats they might have built.
Skilled shipbuilding technology, however, need not have been required. In 1947, Norwegian explorer and writer Thor Heyerdahl proved that a primitive reed craft was capable of crossing the wider Pacific Ocean when he set out to prove that South Americans could have traveled to Polynesia. He set out from South America and successfully crossed the Pacific, finally landing on an island in his target destination.
Additionally, both Norse and English people are known to have crossed the Atlantic in craft that were not technologically sophisticated.
A link between the Solutreans and Clovis People will likely be argued for years. The similarities between the two cultures would seem to be based on more than happenstance. Solutreans, possibly from what is now Spain, could be the people who discovered America.
The Clovis people disappeared from the archeological record some 10,500 years ago. This was about the time when the last ice age ended. Climate change is believed to have affected many of the large mammal species on which the Clovis people depended.

The life of winter

Adventures on Earth column for the Dec. 1 edition of The Review
By George E. Beetham Jr.
Many people stop hiking during the cold winter months. Yet winter is a great time to get outdoors and check out what’s going on in the natural world.
Some people look at the natural world in winter and see a dead world. Nothing could be further from the truth. The forest is very much alive, a fact that will become readily apparent if there is snow on the ground.
That is when the creatures that are out and about leave tracks in the snow.
That is when a person can see that there really are turkeys in our woods – a fact that the otherwise elusive creatures tend to obscure the rest of the year.
In fact, if you are so inclined, you can follow turkey tracks through the forest and get an idea of what life is like for turkeys.
Deer also lurk in the winter forest, their long gray fur helping them to blend in to the black and gray forest.
Winter is not an easy time for deer. Most of the greens they eat during the growing season are gone in winter. Deer must settle for whatever they can dig up from the snow or the tips of woody shrubs and trees.
Bear may or may not be dozing the time away in their dens. Black bear, the kind that inhabit the East, are light sleepers that emerge on warmish days to prowl about in search of food.
Bear will dine on mast during winter – the acorns and other nuts that fall from trees and lie about on the forest floor.
Bobcat and coyotes roam the winter forest looking for deer or other creatures that can make a meal. Their chances of success in winter are increased if deer cannot get as much food as they need to stay healthy. It’s nature’s way of weeding out the weak and lame.
Squirrels and over-wintering birds flit through the forest, chipping or chirping alarms as two-legged intruders lope along a trail.
Some hawks and owls winter in the region, squirrels, rabbits, and birds on their winter menu.
Unless it gets unseasonably warm the insect world is gone from the winter forest. Many insects lay eggs and die before the cold sets in. Their eggs will hatch on warm days, filling streams with larvae and providing an early spring meal to fish and other aquatic creatures.
The leaves are gone from deciduous trees and from tamarack. Pines, spruce, hemlock, and balsam break up the gray-brown of the winter forest, accent points of green.
When high and low pressure align close together, the pressure differential between the two can force cold winds to descend from the north.
On days when that happens, trees groan and creak as they flex. At times a tree is bent too far and cracks with a loud report that sounds like a gunshot. It hits the ground with a thud. It’s an alarming sound, especially so since there are trees all around that are bent from the force of the wind.
Ice flows from cliffs like frozen waterfalls. When sunlight glints off the ice it seems almost alive as it sparkles.
Waterfalls freeze as well, with water sometimes still running amid the columns of ice. If the ice has built up over time it can be quite impressive.
On days when the temperature warms up a bit, another bit of geology can take place. Freezing water acts like a wedge in the cracks and joints of rock formations. When it warms up rock breaks loose and falls from cliffs.
Frost heaves push up from loose earth, another feature of the freeze-thaw cycle.
If you are lucky enough to be in the forest after fog freezes on trees and shrubs, you will delight in rime ice, appearing like frosting on a cake.
All of that and more can be found in the winter woods for those who get out and enjoy the life of winter.
Remember to wear sturdy, waterproof foot gear and to dress in layers. When hiking it’s good to avoid over-heating by removing a layer or two. When stopping to take a break, adding layers will keep you warm.
Enjoy the life of winter.

A weakening magnetic field

Adventures on Earth column for the November 24 edition of The Review

By George E. Beetham Jr.
A program on one of the cable science channels delved into Earth’s interior. In a two-hour program, they gave detailed explanations of what each of the four layers below ground is and how it affects the world in which we live.
Of course, we know best about the surface of the planet. We’ve lived in its embrace for thousands of years, so we have a lot of experience dealing with it and its foibles.
We know about earthquakes, volcanoes, hurricanes, tornadoes, rogue waves, and all the other ways the planet has to either take our lives or make life miserable for a long time.
We even know how the mantle – the region of hot, viscous rock – moves continents around the globe through heat convection.
It is the outer and inner cores that continue to mystify us.
The outer core is thought to be made up of liquid iron, or maybe many molten metals. Convection currents in the outer core may be responsible for variations in mantle temperature.
But it is the spinning of Planet Earth on its axis that agitates the outer core, spinning hotter matter around and keeping the pot stirred.
The inner core is solid iron. We know this because seismic recording devices bounce off the inner core when earthquakes occur. Around the world these readings show the inner core and its relative size.
While the inner core is hot, it is cooler than the outer core. It is now thought that the inner core is slowly expanding as the planet cools. In time, the entire planet will cool to a point where it will consist of solid material from surface to center.
That date is many millions, likely billions of years ahead of us. In the meantime a more pressing matter needs attention.
The Earth is protected from solar radiation by its magnetic field. As solar flares shoot radiation far from the sun as solar wind, the solar wind is deflected around Earth by the magnetic field.
The magnetic field is generated by the inner core, which sends out electrical pulses that create the field. Once thought to act like a dynamo, the electrical charge is what generates the field.
At both poles, the interaction between solar wind and magnetic field can be seen as aurora – the shimmering northern and southern lights.
When a large mass of solar radiation is released and shot outward, the aurora can be seen many miles away from the poles, even over eastern North America.
Over time, for reasons we don’t yet understand, the polarity of Earth’s magnetic field flips. What is now the north pole becomes the south pole and vice versa.
We know about polarity flips because the magnetic orientation is recorded in molten magma that cools and becomes solid. As the rock solidifies, the magnetic orientation is locked up as iron molecules orient themselves along the magnetic plane.
Earth is very likely in the early stages of just such a flip right now. First, the magnetic field is slowly weakening. East of Brazil in the Atlantic Ocean, the magnetic field has disappeared altogether.
Moreover, by studying the time between polarity flips, it appears we are about due for one to occur.
No human has lived through a polarity flip. The last one took place an estimated 700,000 years ago. So we don’t know exactly what will happen as the process plays itself out.
We do know that solar radiation would likely increase as the magnetic field weakens and stops. But we don’t know what that means for life, particularly human life.
But the Earth has gone through polarity shifts many times, and life has continued right on through the shifts.
We don’t know when the shift will happen and we don’t know how long it will take for the process to play out. There are these events that science cannot yet describe.

No rise in storms from global warming

By George E. Beetham Jr.
Adventures on Earth column for the Nov. 17 edition of The Review
Conventional wisdom held that global warming would mean higher sea surface temperatures and thus more and stronger hurricanes. It turns out conventional wisdom was wrong.
While the first part of the statement is true, warmer sea surface temperatures are virtually certain, the threshold for tropical cyclone formation would rise from the current 80 degrees Fahrenheit.
This means it would take warmer sea surface temperatures to trigger storm formation.
Hurricanes form as low pressure systems move over warm, tropical seas. At 80 degrees, the warm water evaporates and the warm, moist air rises, eventually forming clouds. The counter clockwise rotation of air around the low and the rising warm air funnel more and more moisture into the clouds.
As the speed of winds rotating around the low increase the storm draws more warm air inward. The rotation contracts, and eventually an eye develops.
Researchers at the University of Hawaii’s International Pacific Research Center (IPRC) have discovered that the threshold sea surface temperature for the convection of warm, moist air is rising at the same rate as the warming of the tropical seas.
The researchers studied records dating back 30 years and found that the threshold temperature closely followed the increase in average sea surface temperatures in the tropics. Both have been rising at the rate of one degree centigrade per decade.
Nat Johnson, lead author of the study and a postdoctoral fellow at the IPRC, said, “The correspondence between the two time series is rather remarkable. The convection threshold and average sea surface temperatures are so closely linked because of their relation with temperatures in the atmosphere extending several miles above the surface.”
Johnson and co-author Shang-Ping Xie, professor of meteorology at IPRC and University of Hawaii Manoa, found that temperatures in the upper atmosphere have been rising at the same rate as sea surface temperatures and the convection threshold.
The study means that global warming will not bring more frequent hurricanes as conventional wisdom had supposed.
The study also means there is no linkage between the increase in storm frequency in recent decades and global warming. Instead, tropical cyclone formation tends to run in a cycle of approximately 70 years.
The current cycle began with a peak about 1950 and the next peak would occur in 2020, assuming the 70-year cycle to be accurate.
One of the difficulties in tropical cyclone prediction is that accurate records only go back to the middle of the last century. Models of cyclone formation are thus based on relatively little data.
Still, the cyclical nature of cyclone formation appears to hold true in the Atlantic.
What meteorologists still have not determined is what effect, if any, global warming will have on storm intensity.
As scientists continue to focus on global warming and the effects it will have on weather, that question too will likely be answered sooner rather than later.
For the record, the Atlantic hurricane season is winding down, with just two weeks left before it ends. While it was a busy season, it fell far short of 2005, the record year.
This year there were 19 named storms of which seven were hurricanes with four of those reaching Category 4.
In 2005 there were 28 named storms (one of which was sub tropical) and 15 hurricanes, of which eight were major storms.

Farming in autumn

By George E. Beetham Jr.
Adventures on Earth column for the Nov. 10 edition of The Review
We are speeding our way through another calendar year. We are done with Daylight Saving Time. Thanksgiving is two weeks away, and winter is less than six weeks away. Autumn is half gone.
The leaves are mostly gone from the trees. What remains will be gone shortly. Hurricane season ends at the end of the month, and an active season it has been.
We’ve had a frost, at least in outlying areas if not the city proper.
In short, the natural world, for all intents, is into winter.
I can remember a November trip to my grandparents’ farm in Bucks County when I was a child. The farm was on a hill, and the wind howled over that hill. It was cold, colder than I had expected.
We were getting the hard corn ready for the mill. We called the hard corn horse corn. It was not the sweet corn that we eat, but corn raised specifically to be milled into feed for the herd of dairy cows.
We would feed the ears of hard corn into a mechanical sheller, driven by a belt off the tractor, that would strip the kernels of corn off the cob.
The kernels would tumble into a burlap sack and the cobs would be spit out the back into bushel baskets.
There were many uses for the cobs. My grandfather would use them as handles for files and knives that served several functions on the farm. They could also be broken up and spread as mulch on the fields.
For the kids, they were perfect for chucking at one another, and corn cob fights were not uncommon.
We worked at the job in spite of how cold it felt. I was not adequately clothed for that cold, and I remember being very uncomfortable and even more unhappy. Still, we worked until the job was finished and we retired to the farm house for hot chocolate with marshmallows and the warmth of a wood stove in the kitchen.
Ever since that day, the first really cold snap of autumn takes me right back to that day in the corn crib shelling the corn.
In the days when agriculture was a staple of our economy, a lot of people marked the passage of a year by what took place on a farm. Farm chores are cyclical, just like weather, and farmers spend the harvest season getting ready for winter.
During the growing season farmers plant, cultivate, weed, and nurture their crops. When they are ready for harvest, that becomes the next step in the progression of a farm year.
By late autumn, there are only a few jobs left, things set aside when more pressing business took precedence.
Over the winter it was necessary to feed, water, and milk the cows, shovel out the manure, and put down fresh straw. The cows chewed their cud and produced milk, along with the manure.
Cold weather, snow, ice, and howling winds made a farmer’s chores all the harder during the cold months, not unlike the challenges posed for city living.
If farming life was hard, it was also rewarding. As part of the harvest, food was put up, either canned in Mason jars or frozen. Thus the produce was available all year long in one form or another.
Those days are long gone, relegated to memory and dreams. But a brisk wind out of the northwest brings it all back in seconds – those days when late autumn made the chores a lot harder.

Where fire and ice meet

Adventures on Earth column in The Review for Nov. 3, 2010.
By George E. Beetham Jr.
When Eyjafjalla in Iceland erupted last spring, it was assumed by volcanologists that a nearby volcano would follow. Katla still has not stirred to life as expected, but another volcano is rumbling.
Grimsvotn is a volcano that lies under an ice sheet (jokull in Icelandic), just as Eyjafjalla and Katla do. Grimsvotn is located northeast of Katla under an ice sheet that is far larger.
On Oct. 2 and 3, tremors were detected under Grimsvotn. That was followed by a small earthquake last Thursday, then flooding in the Gigjukvisl River.
The flood was caused by meltwater from the ice sheet, the melting caused by heat rising from a magma chamber under Grimsvotn.
Grimsvotn last erupted in 2004, then causing disruption of air traffic in Europe as the ash plume flowing from Grimsvotn drifted southeastward.
At that time there was no appreciable melting of ice, but a 1996 eruption did cause a meltwater flood.
These floods are known as glacial bursts (jokulhlaup in Icelandic). In 1996, the glacial burst occurred weeks after the eruption ended, flooding downstream to the sea. That glacial burst was predicted, allowing authorities to shut down the Icelandic ring road that circles the island.
Iceland is located athwart the Mid-Atlantic Ridge, a chain of volcanic fissures that spread outward, moving the ocean plates of the Atlantic away from the fissures.
The ridge surfaces on a peninsula southeast of the capitol city of Reykjavik, slicing northeastward, then eastward then northward to split the island. An arm of the fissures extends southward, and it is on this arm that Grimsvotn, Eyjafjalla, and Katla are located. Farther to the southwest is Surtsey, a volcanic island which emerged from the sea on Nov. 14, 1963.
Volcanologists relatively recently determined that water and volcanoes are an explosive mix. When water seeps into the volcano it is superheated, increasing pressure. When the pressure builds up sufficiently, there is a violent explosion with ejection of masses of volcanic ash, rock, and lava.
It was this kind of eruption that blew the top off Mount St. Helens in 1980 and Pinatubo in the Philippines in 1991. It was also the cause of the Eyjafjalla eruption last spring as well as previous eruptions of Katla.
In all three Icelandic cases, the volcanoes are topped with an ice field, the source of water once magma builds up and releases heat.
What happens next at Grimsvotn is anybody’s guess. Volcanologist think it will erupt violently, but a violent eruption of Katla was expected in the wake of Eyjafjalla and it has not happened.
The eruption of Eyjafjalla last spring spewed tons of ash into the atmosphere, shutting down air travel over Europe. When volcanic ash is ingested by jet engines, it can destroy the engine and cause the plane to crash.
That disruption of air travel cost money to airlines and to businesses dependent on air travel. An eruption of Grimsvotn could do the same thing, perhaps for a longer time.
Meanwhile, flooding from the volcano is an immediate threat to Iceland’s ring road and bridges. The ring road bridge over a sandbar was washed away in the 1996 flood.
Because of its location astride the Mid-Atlantic Ridge, Iceland and its volcanoes will continue to threaten air traffic disruption over Europe, as well as flooding on the island nation.
Iceland has been called a land of fire and ice. Where the two meet, things are bound to happen.

Storm intensifies, but expected to turn out to sea

The tropical wave that the National Hurricane Center was tracking near the Windward Islands intensified as expected into Tropical Depression 17. The National Hurricane Center is forecasting the storm to curve away from its northwesterly track to a northeasterly track - a track that would take it far out into the mid-Atlantic. The turn will take place in the next 24 hours. The storm is expected to intensify into Tropical Storm Otto by that time, but it is not expected be a threat to the East Coast.

New storm brewing

Forecasters are following another tropical wave that is now dumping rain on the Windward Islands, Puerto Rico, and the Dominican Republic. The wave currently has sustained winds at 30 miles per hour, but it is expected to intensify into a tropical depression sometime Wednesday afternoon and perhaps become Tropical Storm Otto by Thursday. Given the flooding of last week, keeping a weather eye out for this storm would be prudent, particularly if you live or work near the Schuylkill River.

Humble seeds

Adventures on Earth column for the October 6 edition of The Review
The Manayunk Canal was a short section of what was the interstate highway system of the late 18th and early 19th centuries. Up and down the eastern seaboard, canals followed waterways that carried the commerce of the new nation.
The Manayunk Canal is a skirting canal. That is, the canal skirted Black Rock Falls.
Skirting canals were the first canals in the United States, built on the fall line where river gave way to estuary.
Below the fall line, the estuary provided a fast, economical means of transporting goods and raw materials.
Above the fall line, bateaux, rafts, and Durham boats carried goods up the river and raw materials down the river. Above the fall line navigations was subject to rapids and other obstacles.
The idea of a through canal provided an easy navigational route – smoother transportation than hauling goods on wagons over rutted, rocky, muddy roads. There was less resistance in the water than on wagon roads. Larger and heavier loads became possible on canals.
The Schuylkill Navigation was not a through canal, but a series of skirting canals linking long stretches of slackwater navigation behind dams that also provided water for the skirting canals.
The Delaware Canal was a through canal linking Easton and Bristol. Travel on the Lehigh Canal extended navigation on those rivers into the anthracite fields of Eastern Pennsylvania.
Canals, out of necessity, followed rivers upstream. Rivers provide the easiest grades, meaning less locks were required to lift of lower boats as they moved up or down the canal.
In their day, canals were a very practical solution to transportation challenges. But they also had two serious drawbacks; they were subject to freezing in winter and flooding at any time of the year.
Navigation halted for winter and after floods. Goods could not be moved during times when the canal was out of operation. For that reason, railroads came into being. Like canals, railroads followed river routes, at least in the early days. But they could operate year round and were easily rebuilt following floods.
Canals, and later railroads, were engineering marvels in their time. The underlying geology was often an obstacle that engineers had to overcome, whether digging into rock or shoring up berms or towpaths. Locks were likely the most complicated engineering challenge.
The Union Canal between Reading and Middletown on the Susquehanna faced several serious engineering challenges.
First, the summit level of the canal – the highest elevation on the canal – was near Lebanon in the Great Valley. The Great Valley is underlain by limestone, which is soluble in acidic water. The engineers had to use lumber to line the canal and keep the water from leaking out.
The summit level was also higher than any water source, so the Union Canal builders had to construct a pumping station to take water from the Swatara Creek up to the summit level.
Then a ridge northwest of the town was an obstacle that was overcome by drilling a tunnel through the rock to carry the canal and towpath under the ridge.
All of that contrasts to the Schuylkill Navigation, where dams and skirting canals posed less of an engineering challenge where much of the navigation was provided by nature.
Railroads eventually replaced canals, which lingered on in some cases into the 20th Century.
The canals that have been preserved also face challenges due to periodic flooding. But they have value by reminding us that the transportation network we now have grew from humble seeds.

Philadelphia Police Dept. Flood Plans

For Immediate Release
September 30, 2010

Flood Condition Plans
Thursday, September 30, 2010


In the event that a weather emergency is declared due to flood conditions throughout the city, Police Department personnel will be deployed to the following locations to implement street closures as the need arises:

Columbus Boulevard
Kelly Drive
Lincoln Drive
Martin Luther King Drive
Main Street in Manayunk
Roosevelt Boulevard
Cobbs Creek Parkway
Although the aforementioned locations are typical hotspots for flooding conditions and downed trees, there is the possibility that many other areas will be affected by flooding and high-winds as well. Thank you for your cooperation during this possible weather emergency.

Flood warning and tornado watch this afternoon and evening

Philadelphia is under a flood warning and a tornado watch until 7:45 this evening (Thursday) as remnants of tropical storm Nicole and a large low have merged and are moving northeastward up the coast. Heavy rains associated with this huge storm have caused flooding to our south.

Flood watch continued into Friday

What was Tropical Storm Nicole was absorbed into a low pressure trough along the Mid-Atlantic seaboard and was causing heavy rain in North Carolina on Thursday morning. The trough will continue to move through the region into Friday as moisture to the south moves northward. The flood watch for this area continues into Friday. Flood warnings were posted to the west this morning. A flood warning means that flooding is either imminent or occuring.

Area under flood watch until Thursday night

The National Weather Service has issued a flood watch for Philadelphia and the region. The flood watch extends until Thursday night.

According to the National Weather Service, low pressure associated with Tropical Storm Nicole will move up the East Coast tonight and Thursday. With extremely high moisture content... a strong storm inflow... and lots of instability... rain beginning tonight will be heavy at times later tonight and especially Thursday. The rain should taper off Thursday night as the center of tropical low pressure moves north of our area.
Total precipitation is expected to average 2 to 4 inches... but local amounts may be up to 6 or 7 inches. Although the forecast could change... at this time the greatest precipitation is expected over the northeast Maryland shore... eastern Pennsylvania... Delaware... and western New Jersey. Slightly lesser although still heavy amounts may occur closer to the New Jersey coast.

Tornado watch this afternoon

The region is under a tornado watch until 6 p.m. Tuesday. The National Weather Service reminds that a tornado watch means that a tornado is possible. If signs that a tornado is forming NWS will issue a tornado warning. However, there may not be sufficient time if a tornado develops rapidly.

Storms associated with the passage of a cold front result from unstable air, conditions that are favorable for tornado development.

New tropical storm threatens Cuba, U.S. East Coast

Tropical Depression 16 is approaching Cuba on Tuesday afternoon. The National Hurricane Center expects the storm to strengthen into a tropical storm. It would weakend somewhat over Cuba, but will emerge and pass up the eastern coast of Florida, then head toward the South Carolina-North Carolina state line by Thursday morning, according to NHC predictions. strengthening in the Atlantic is likely.

Dynamics of the Planet

Adventures on Earth column for the September 22 edition of The Review

Some of the oldest rock on Earth can be found in what is called the Canadian Shield, a circular shaped belt of rock running from Greenland down to the northeastern US border, and then westward over the Canadian prairie, then up to the Arctic Ocean.
Most of the rock in the formation was laid down from 2.45 to 1.24 billion years ago.
It is the foundation upon which the rest of North America was built. Unlike parts of the United States, the Canadian Shield never was covered by sea.
In two places the Shield dips just a bit into the United States: the Upper Peninsula of Michigan and the Adirondack Mountains. It is the Adirondack Mountain section that we will examine here.
The Adirondack Mountains of New York State are unique among American mountain chains. American mountains are generally uplifted as the result of collision of continental land masses.
The folding and faulting of mountains results from lateral compression when two land masses are pushed together.
The rocks of the Canadian Shield were formed this way in what was known as the Grenville Orogeny. An orogeny is a pulse of mountain building that takes place when continents collide.
The Grenville Orogeny brought the Canadian Shield together with what are now parts of Europe into a supercontinent that geologists call Rodinia. Rodinia eventually broke up, but then the continents came together again during the Alleghenian Orogeny that formed the supercontinent called Pangea. Pangea, in turn, broke up to form the present array of continents and islands.
After the break-up of Rodinia, the Adirondacks eroded away into an elevated plain (called a penneplain) like the rest of the Canadian Shield. Unlike the rest of the Shield, the Adirondacks were submerged under a sea. Sediments covered the Shield rock.
During the Tertiary, which began 65 million years ago until 1.6 million years ago, the Adirondacks began to rise. Geologists think a hot spot developed in the mantle below the continental rock.
Hot spots are upwellings of the viscous mantle rock. Hawaii and Yellowstone are two places located over hot spots. As ocean or continental plate moves over a hot spot, volcanoes form. As the plate moves, the hot spot remains fixed.
A hot spot under the Adirondacks would seem to be fairly new by geologic standards. Hot spots usually form a chain of volcanoes or scars on the land. There is no such chain for the Adirondacks.
The mountains continue to rise at the rate of 2-3 millimeters a year, very rapid by geologic standards.
What does this mean for the future? The Adirondacks will continue to rise, although the rate will vary, for some time to come.
What could happen next, as the mountains rise, is that the rock will stretch. At some point it will break, forming the beginnings of a rift valley. Parts of North America will drift apart as the sea spreads into the rift valley.
None of us will be around to witness the process, but eventually land masses will again begin to move together. That process is the dynamics of the planet.

Moving islands

Adventures on Earth column for September 15 edition of The Review
Continuing with our discussion of barrier islands, recent research seems to explain why some barrier islands continue to grow as sea levels rise and other to sink into the sea.
Conventional wisdom would seem to dictate that all barrier islands are in danger of being submerged as sea levels rise. But that is not the case.
As sea levels have risen, some barrier islands continue to migrate toward the mainland and stay above the waves.
Others migrate so slowly that rising sea levels overtake the natural course of replenishment.
The difference seems to be the base on which a barrier island stands.
Islands with a sand base, like North Carolina’s Outer Banks, are able to migrate ahead of rising levels. That is because there is plenty of sand at hand to replenish what would otherwise be lost.
As storms scour the seaward side of the islands, sand it washed into the sound where it accumulates on the landward side. And in some cases, beaches eroded in storms are later replenished as sand is transported through currents known as longshore drift.
Sand and sea interact, the sea moving sand from one area and depositing it in another.
In the case of the Outer Banks, inlets form and close as the sea overwashes the island, or transports sand to fill in the inlet.
Sand continually drifts into inlets, which are dredged to maintain channels for maritime shipping.
The configuration of Outer Banks islands is not the same as it was in Blackbeard’s time. Blackbeard was a master of navigation between shoals. He would be at a loss today because channels he used have filled in and new channels have replaced shoals.
Islands have changed their shape as the sea rearranges sand to suit its fleeing whims.
All of that rearranging of sand gives the barrier islands of the Banks a strong foundation, allowing sand to build up.
Barrier islands along the Gulf of Mexico coast are not based on sand, but mud that is deposited from rivers flowing into the Gulf. It is mud that forms the Mississippi Delta and the bayous along the coast.
The mud is not a stable base, so as sea level rises islands tend to sink.
Researchers have studied the Chandeleur Islands off Louisiana. Those islands are not able to reacquire sand as they migrate landward, so they are slowly sinking.
The researchers are turning their attention to other barrier islands. Those off the coast of Virginia and Maryland and other areas of the Gulf Coast will be studied to see if the patterns hold up there.
Barrier islands, remember, protect the coast from storms. As storms approach the barrier island is hit first. Robbed of heat and moisture from the sea, the storm loses its punch. The barrier island also absorbs storm surge that otherwise would be more damaging inland.
If barrier islands are lost, storms will vent their full fury on the coast.
The attempts of humans to protect barrier islands through breakwaters or sea walls interfere with the transport of sand and ultimately work against the intentions of the builders.
As currents transport sand, it eventually ends up where it will help rebuild the island as it moves.

Here come two more

Hurricane Igor is roaring its way across the tropical Atlantic, a Category 4 storm that will likely intensify to Category 5. Igor formed just off the coast of Africa on Sept. 7. For several days it meandered in the area of the Cape Verde Islands, over cooler waters. The storm showed good tropical storm formation, though, and after it moved into warmer waters to the west it intensified rapidly. As of Monday morning it was approaching the Leeward Islands, but the National Hurricane Center predicted it would turn to the northwest, and then more northward, heading toward Bermuda.

Next up was Tropical Storm Julia, which also formed off the coast of Africa in the vicinity of Cape Verde. It grew into a tropical storm on Monday and is tracking generally westward. It, too, is over cooler water but is likely to intensify as it moves into warmer water to the west. The National Hurricane Center predicts it will move more northwestward to the east of Igor.

Meanwhile, NOAA predicts the current La Nina pattern over the tropical Pacific will continue intensifying into winter. This will increase the likelihood of tropical cyclones in the Atlantic.

And then, nothing

That quickly the storms in the Atlantic either dissipated or went north. As of 5 p.m. Saturday, Tropical Storm Earl was in the Gulf of St. Lawrence after battering Nova Scotia with tropical storm force winds. Earl made a glancing pass at the Outer Banks and Cape Cod, but otherwise passed out to sea on its route north.

Fiona and Gaston fizzled out, although the disturbed weather that was Gaston continues across the tropical Atlantic. Meteorologists are monitoring a disturbance in the Gulf of Mexico and another near the Cape Verde Islands. Other than that, the Atlantic is quiet. Clear, cooler air has descended over the eastern part of the country. Enjoy the respite. Hurricane season still has nearly three months of potential surprises.

Life in a marginal habitat

Adventures on Earth column for the September 8 edition of The Review
Again the Outer Banks in North Carolina experienced overwash from a hurricane. Several years ago Route 12, the main highway along the Banks, was severed at Mirlo Beach just north of Rodanthe.
Storm surge from Hurricane Earl apparently washed over the highway in several places and severed the route, isolating communities to the south.
The Outer Banks are barrier islands – a thin strip of sandy land lying offshore. The islands are cut during storms and then fill in as ocean waves move sand up and down the beaches.
The barrier islands generally protect the mainland from storms, taking the brunt of storm surges and often deflecting storms back out to sea.
They are marginal places where life clings to a tenuous existence. Many creatures use the islands to nest or propagate.
Storms and currents move sand, making maritime navigation tricky. Pilots must know the locations of shifting sand bars as they follow dredged channels on their routes from ports to the sea.
The pirate Edward Teach (or Thatch), known as Blackbeard, used his knowledge of channels and sand bars to elude British navy patrols, but finally met his end off the island of Ocracoke in a battle with a British patrol as they maneuvered between sand bars..
Barrier islands are not stable land masses. The Outer Banks is moving slowly west, a progression that has been taking place for centuries. To the west of the existing Banks, a thin ribbon of sand is accumulating in Pamlico Sound – the next stand of the barrier islands.
At times, tree stumps are uncovered by ocean waves. The trees were once on the western side of the island, but as the island moved west the tree stumps ended up on the east side.
All of this is to say that barrier islands and hurricanes are part of the natural progression. If no humans moved onto the islands, the process would go on at the whims of nature.
It is the human incursions that create issues. Humans build on the islands, then go about stabilizing the sandy strips in order to protect their investment.
When storms hit, beaches erode, homes fall into the sea, and islands are cut in two, isolating communities until workers can fill in the newly created inlets and restore the roads.
In the memory of living people, hundreds of yards of ocean front have been eroded away. Homes that were once far from the beach are now washed by waves at high tide.
Walking along isolated Outer Banks beaches, one finds not just shells and nautical debris, but bits and pieces of what were once homes wood panels, framing, plumbing fixtures, sometimes entire walls.
This is what happens when people build on barrier islands. The Jersey Coast is another place where the eternal battle between people and nature takes place.
Municipalities spend fortunes replenishing beach sand, piping it from offshore back to the beach. The process repeats after storms over and over again.
Earl’s glancing blow wreaked havoc not with barrier islands, but with what humans put on those barrier islands. Islanders know that when they build out there their building will ultimately meet its fate in some storm.
Had Earl made landfall or a more direct blow, the damages would have been much worse. As it is, Outer Bankers will roll up their sleeves, repair damages, fill in new inlets, rebuild roads, and life will go on.
It always does in marginal habitats.

Hurricane Earl was downgraded from a Category 4 to a Category 3 storm as of 2 p.m., but still carrying a powerful punch. As it moves north the storm will be over slightly cooler water.

Earl is expected to make a glancing blow at the Outer Banks late tonight and another glancing blow at Cape Cod early Saturday. Later Saturday it is expected to plow into Nova Scotia as a Category 1 hurricane.

The projected path is well out to sea except for the Outer Banks and Cape Cod. Still, Earl will stir up heavy surf and perhaps a storm surge as it passes up the coast. Authorities warn against swimming or surfing.

There is also a slight chance the storm could deviate from its anticipated path and move inland. Keep a weather eye out for this storm in the next 36 hours.

Earl should pass out to sea; more storms coming

Hurricane Earl, strengthened again to a Category 4 storm with sustained winds of 145 miles per hour, was expected to graze the Outer Banks Thursday night and Friday morning before curving out to sea. Hurricane warnings were posted along the entire coast all the way to Cape Cod.

Even if Earl passes out to sea, heavy surf and storm surge remain threats along the coast. Authorities warn of dangerous undertow that can carry swimmers or surfers far out to sea.

The National Hurricane Center forecasts that Earl will pass off Cape May about 2 p.m. Friday.

Meanwhile, Tropical Storm Fiona appears to be curving northward and should track well out to sea. Another storm, Gaston, emerged as a tropical wave off the African Coast on Monday. It was upgraded yesterday to a tropical storm with winds at 40, but downgraded today to a tropical depression. Sea surface temperatures are favorable for storm development, so Gaston bears watching as it crosses the tropical Atlantic.

Yet another tropical wave emerged off the African Coast today. Stay tuned; we are in the peak of hurricane season in what promises to be a busy year.

Trouble brewing in the Atlantic

Hurricane Earl, now a Category 4 storm with sustained winds of 135 miles per hour, continues on a course that is projected to take it up along the Atlantic seaboard. Meanwhile, Tropical Storm Fiona threatens to overtake Earl and perhaps the two storms will merge.

Fiona's track is nearly the same as Earl's. Earl is moving at 13 miles per hour west-northwest. Fiona is moving at 24 miles per hour, also west-northwest. Both storms are skirting the Leeward Islands.

A large area of high pressure had settled over the eastern states and will dominate weather until later in the week. This will keep the storms out to sea, but their effects are likely to be felt along the coast. Earl is expected to reach the Outer Banks Thursday night and pass off the Jersey Coast on Friday.

Meanwhile, a new disturbance formed in the Eastern Atlantic late Monday.

Hurricane Earl headed up the coast

Forecasters at the National Hurricane Center project that Earl, a Category 4 hurricane with 135 mile-per-hour sustained winds as it brushed past Puerto Rico on Monday, will head up the Atlantic Coast later this week. It is projected to be off the Outer Banks by Thursday evening and off the Jersey Coast on Friday. Unlike Danielle, now downgraded to a tropical storm as it heads northeastward across the North Atlantic, Earl is tracking farther westward.

Meanwhile, another tropical storm was spawned Monday by a tropical wave that passed from the West Coast of Africa last Thursday and intensified late Monday into a tropical storm. Named Fiona, it was poorly organized Monday and following pretty much in Earl's wake across the tropical Atlantic.

Anyone planning coastal vacations beginning later this week should keep an eye on developments from Earl, and possibly Fiona.

Creating a haven

Adventures on Earth for September 1 edition of The Review
By George E. Beetham Jr.
The Earth formed some 4.6 billion years ago as material came together to form the planet. For another billion years, the planet would consist of rock and sea.
The seas were not the oceans of today. They were a primordial mix of chemicals that are toxic to life as we know it.
While there may have been some form of life present in those toxic seas, it would take the emergence of one life form that would transform the planet and open it up to life.
Cyanobacteria, or blue-green algae, synthesized sunlight to create energy, taking in carbon dioxide and giving off oxygen.
The cyanobacteria clumped together in mats on the floor of warm, very shallow seas. The organisms trapped sediments that cemented together, forming dome-shaped structures.
As the structures grew, the cyanobacteria moved up, reaching for the sun, staying above the now hardened structure below.
The structures are known as stromatolites. Stromatolites are among the planet’s earlies life forms, forming some 3.5 billion years ago.
Throughout the history of the Earth, stromatolites have ebbed and flowed. After their formation, living creatures grazed the algae at the top of the structure. When grazing creatures thrived, stromatolites began to disappear, emerging again when mass extinctions wiped out the grazers, and then waning as new grazers arose in the wake of the extinctions.
Today stromatolites are found at about a half dozen to a dozen known sites, some in oceans and some in lakes and inland seas.
They have been found in two locations in Western Australia and in the Bahamas.
Some were found in Yellowstone National Park.
Stromatolites are abundant in the fossil record. In particular, the Keyser Formation at the Silurian-Devonian boundary is noted for vast reefs of stromatolites.
A cliff in western Virginia shows stromatolites crowded together, one layer on top of another.
Stromatolites begin as small structures, growing outward as sediments get cemented. The layers are not unlike a cabbage or onion. Cross section of fossil stromatolites show this layering very well.
Because cyanobacteria have an unpleasant odor, biologists dubbed them “stinking cabbages.”
Unlike cabbage, stromatolites are hard rock in their interior. It is only on the upper outer surface that the cyanobacteria form.
Stromatolites are likely to endure as long as conditions are favorable on the planet. They will almost certainly outlive humans.
As living things go, stromatolites are less than spectacular. There is no colorful flower, no bright plumage, no luxuriant fur. There is just the cabbage-like head with perhaps a stalk below. They can surface at low tide and be submerged at high tide.
Yet they have endured through thick and thin for 3.5 billion years and will likely be around for another 3 billion or so years.
They gave us oxygen and made the planet a haven for life.

And now there are three

Tropical storm season kicked into high gear this week as Hurricane Danielle continues to track southeast of Bermuda, Tropical Storm Earl is heading toward the Windward Islands, and a new disturbance that came off the coast of Africa on Thursday is being watched by forecasters for possible development.
Danielle is expected to turn north, and then northeast, passing east of Bermuda on Saturday. Dangerous surf conditions will prevail in Bermuda and swells from Danielle will reach the US Coast on Saturday, creating dangerous rip currents.
Danielle is a Category IV hurricane with sustained winds of 135 miles per hour. The storm developed an eyewall on Thursday.

Earl is still a few days from making any landfall, but is slowly gaining strenth. It's sustained winds are at 45, but barometric pressure is slowly dropping.

The new disturbance was south of the Cape Verde Islands on Friday. Winds increased from 20 to 25 miles per hour from Thursday into Friday.

Now there are two named storms in the Atlantic

Hurricane Danielle strengthened today and has charted a course toward Bermuda. As of 5 p.m. Thursday, Danielle packed sustained winds of 110 miles per hour and was moving northwest at 14 miles per hour. The National Hurricane Center placed Danielle at 25.2 North, 57.0 West.

Tropical Depression 7 became Tropical Storm Earl on Wednesday afternoon. At 11 a.m. Thursday, Earl was at 14.9 North, 37.1 West, with sustained winds at 45 and moving west at 17 miles per hour. That location is at the middle of the Atlantic with a course toward the Windward Islands.

Sea surface temperatures and weather conditions are favorable for storm development.

Storm season picking up

A storm that emerged off the coast of Africa last Friday grew into Hurricane Danielle on Monday. On Tuesday the storm had reached the Mid-Atlantic between the Windward Islands and Cape Verde Islands and grew briefly to Category 2. By mid-day Tuesday Danielle encountered wind shear and dropped back to Category 1. The storm is expected to curve more to the north and pass east of Bermuda later in the week.

Meanwhile, another tropical wave passed off the coast of Africa on Monday and is expected to become Tropical Depression 7 later Tuesday and Hurricane Earl either late Tuesday or early Wednesday. This storm is expected to track in Danielle's wake.

Conditions in the tropical Atlantic remain favorable for hurricane development. Sea surface temperatures are well above 80 degrees, the temperature necessary for storm development. The heaviest part of tropical storm season continues into mid-September, with activity now picking up.

News from the Arctic

Adventures on Earth column for August 25, 2010
By George E. Beetham Jr.
Arctic sea ice has been melting during the summer of 2010 at near the record rate set in 2007. With about a month left in summer, this year could still set a new record.
Scientists have discovered that Arctic sea ice melts not from the top down, but from the bottom up. This means the temperature of the water is a larger factor than the temperature of the air above.
It also means the Arctic Ocean as a whole is quickly becoming warmer, and that spells trouble for species that depend on sea ice for their existence.
And that list of creatures is a lot larger than just polar bears and seals.
Indeed, creatures at the very base of the food chain will be affected as sea ice melts. Tiny crustaceans feed on algae under the sea ice. These creatures in turn feed larger predators, all the way up to seals, whales, and polar bears.
This alarming news is contained on a Planet Green Channel documentary, “Oceans Blue – Arctic Ocean,” that aired over the weekend. The cable network will rebroadcast the show at 5 p.m. Friday, 5 p.m,. Saturday, and 8 p.m. Sunday.
The Oceans Blue series is hosted by Philippe and Alexandra Cousteau.
Their work simply adds to alarming news about the Arctic this summer.
● Oceanographers have found that the thickest sea ice, which formerly formed the core around which sea ice reformed during autumn in the Arctic, is floating into warmer waters and it, too, is melting.
● The near record melting this summer follows a late-winter freeze that scientists thought would presage a cooler summer. Instead, it is warmer.
● Forest fires in Russia are affecting ice melt, adding to greenhouse gases and giving off smoke and soot that darken ice.
● Methane hydrates are melting more rapidly than predicted, releasing methane into the atmosphere where it acts as a greenhouse gas.
Sea ice, according to the Oceans Blue documentary, forms at a lower temperature than fresh water ice. As it freezes, it gives off salt, which increases the salinity of the unfrozen water.
Saltier water sinks, helping to drive the ocean currents that carry cold water southward and warm, less saline water northward.
It is this flow of water that helps regulate temperatures around the planet.
When it melts, sea ice is less saline than the ocean water below, so it does not sink. This, some oceanographers fear, could shut down the ocean currents.
If that happens, the Polar Regions would become much colder and a new ice age could set in.
But that would not take effect anytime soon. The immediate reality is that polar ice is melting faster than predicted, and this will affect not just Arctic wildlife, but life around the world.
Ocean levels are rising. They will rise faster as ice continues to melt. This, in turn, will inundate coastal areas that are now dry land.
During the Miocene, ocean levels were higher than they are today. Vast areas of New Jersey, the Delmarva Peninsula, and lands around the Chesapeake and Delaware Bays were under water.
The alarming news from the Arctic means those conditions are likely to return, perhaps within this century.

Relief from the heat

Late August is when the first cold front worthy of the name rolls through, bringing temporary relief from summer heat. One front passed through earlier in the week and another today (Friday). While temperatures have not dropped a lot, they have receded from the upper 90s and lower 100s from just a few weeks ago. The fronts also tell us that autumn, and somewhat cooler temperatures, are coming. It will still get warm, but not oppressively hot for a prolonged period.

The outlook for autumn is for warmer than normal temperatures to continue as the La Nina pattern in the equatorial Pacific continues into winter.

The flipping polarity

Adventures on Earth for August 18, 2010 edition
The latest issue of Earth Magazine examines the issue of the Earth’s magnetic field reversing. The magnetic field has been weakening, a possible indicator that a change is coming.
The questions for which we have no finite answer are when it will occur and what effects it will have.
The Earth’s magnetic field is caused by differential rotation of the solid iron inner core and the molten iron outer core.
There are four zones in our home planet, the solid iron inner core, the molten iron outer core, the viscous rock mantle, and the crustal surface.
The differential rotation of the two inner iron cores acts like a dynamo, putting out a magnetic field that envelops the planet.
The interaction of solar wind with the magnetic field is responsible for the aurorae that dance over polar skies.
Over time the polarity of the magnetic field has changed. The periods between changes vary, so there is no certain time measure.
The polarity flips were revealed when scientists began exploring the issue of plate tectonics, the movement of solid continents on a bed of viscous rock of the mantle.
On either side of the Mid-Atlantic Ridge, where new seabed oozes out, the polarity flips show up as bands.
When molten rock comes to the surface (or to the seafloor), the polarity in effect at that time locks the magnetism of the rock in place. To sort out when flips have occurred, scientists measure the alternating bands and date the rock.
The last reversal took place some 780,000 years ago, a time before humans arrived on the scene. So we don’t know exactly what takes place during the reversal process.
What we do know is that the process can play out over thousands of years in some cases, or in much shorter periods.
In the past, reversals have occurred in relatively rapid bursts, alternating with long periods of quiescence when nothing happens. The current period is apparently one of those long periods of quiescence.
Still, the polarity varies within that long period. We know that magnetic north moves across northern Canada. The movement of the pole requires those navigating by compass to adjust their compasses to magnetic north accordingly. The difference between magnetic north and true north is known as declination.
The magnetic field protects the planet from solar wind. As the magnetic field weakens preceding a polarity flip, there is concern that the loss or weakening of the magnetic will allow solar wind to reach the surface of the planet.
In the past, however, we do not see negative effects on life because of polarity flips. But we live in a highly technical world that can be affected by solar wind. Solar flares can disrupt radio communications, satellites, and shut down power grids.
What will happen and when it will happen remain unknown, but the reversal will happen. Until then, there is time for engineers to study ways to protect against solar wind effects on our technology.

The busiest part of tropical storm season

We enter the busiest time of tropical storm season this weekend. To date there have been three named storms: Hurricane Alex, Tropical Storm Bonnie, and Tropical Storm Colin.

Alex and Bonnie formed in the Gulf of Mexico. Colin formed south of the Cape Verde Islands off the coast of Africa and curled northward. It dissipated near Bermuda.

Sea surface temperatures in the tropical Atlantic and the Gulf of Mexico are warm enough for tropical storm formation as we head into the busy season of what forecasters say will be a heavy year for Atlantic storms.

Warming or cooling

Adventures on Earth for August 11, 2010
By George E. Beetham Jr.
Climate change has been in the news now for several decades. It has been an issue on the planet for roughly 4.6 billion years.
At various times in Earth’s past, the climate has ranged from glacial to tropical. In addition, as continental land masses move around the globe their path takes them through a range of climatic conditions.
As they say, the one constant in the history of Earth has been change.
Change can occur over hundreds of millions of years or it can occur in an instant. The building and erosion of mountains is a slow process that transcends the lives of humans. In contrast, a flood can scour a valley in a matter of hours or an explosive eruption can blow the top off a volcano is mere minutes.
Climate change occurs for many reasons, not all of which are understood. Areas that were once tropical rain forest have become desert and vice-versa. Old seafloor was lifted to form the backbone of Antarctica.
In decades, ocean currents can shut down and plunge a continent into an ice age. In mere seconds, an asteroid can impact Earth and cause widespread extinction.
Recent climate change, though, can be traced to us – humans. Investigators noticed that warming began to increase about the time the industrial revolution and burning fossil fuels began.
As time went by burning of fossil fuels increased. So did planetary warming.
Scientists singled out fossil fuels because the process gives off what are known as greenhouse gases: carbon dioxide, water vapor, nitrous oxide, methane, and ozone are the best known.
These gases tend to seal in heat that otherwise would escape into space, making the Earth warmer just as the glass of a greenhouse seals in heat and creates a rainforest atmosphere in the depth of winter.
At the same time, emission of greenhouse gases under natural conditions, notably volcanic eruptions, has remained fairly constant.
So, while the planet has been in a warming phase since the retreat of the last glaciation some 11,000 years ago, the warming trend made an upward curve in the past 200 years. And remarkably, it was about 200 years ago that anthracite became the fuel of choice in American industry.
Then came the discovery of oil and the dawn of the automotive and air age. Internal combustion engines brought another jump in global warming.
The question we face now is whether we have already reached a tipping point where rapid warming is inevitable or whether there is still time to slow it down.
Regardless of what we do, the fact is that warming will continue. Whether we can rein in warming in time for our children to enjoy the lifestyle we now have is the question.
On the other hand, warming melts glaciers, injecting fresh water into the saline sea. Scientists think that could shut down the ocean currents that now moderate temperatures and bring on a new ice age.
And that change, should it come, could come rapidly.

Auroras and blackouts

Adventures on Earth for August 4, 2010
By George E. Beetham Jr.

A solar flare was expected to reach Earth on Tuesday of this week, perhaps interrupting radio communications and communications satellites and providing spectacular auroral displays at the poles.


The immediate reaction to internet users to the report was concern that the solar flare might pose a danger to life on Earth.

The answer to that question is that solar flares have been erupting in our sun and flying to Earth for the 4.6 billion years our planet has existed.

The only danger, so far as we can tell, would be shortwave radio users bruising their fists pounding on their radios or people in the Arctic and Antarctic straining necks watching the aurora.

How widespread the aurora would be was anybody’s guess when the story broke on Monday. The Geophysical Institute at the University of Alaska Fairbanks forecasts aurora activity, but no report was available for the first three days of August.

There was a slight chance that aurora would be visible in this region, but cloudy skies likely prevented that.

In any event, city lights would have blacked out any aurora that might have been visible from this latitude.

When the sun gives off energy in flares or other ejections, the energy flows outward from the sun. When it reaches Earth, the energy interacts with the planet’s magnetic field.

The aurora is the magnetic field after it is excited by the solar wind.

What we learn from the aurora is that the magnetic field is not static. It ebbs and flows, like ocean waves or wind. The curtains of light shimmer and pulse, sometimes slowly, sometimes more rapidly.

Depending on what matter is carried to Earth from the sun, the aurora can take on colors. Often the aurora is a whitish haze, perhaps with a tint of green.

The aurora are one of nature’s most spectacular displays, particularly when they are more active. As far as the planet is concerned, it is just another day. It has been going on for a long, long time, and it is likely to continue for another long, long time.

Wherever aurora are visible, city lights likely prevent in-town viewing. One has to travel to a dark, rural area to see aurora. Mountaintops are another good place.

Radio communications often black out during solar activity. The ejections excite the radio spectrum, particularly the part of the spectrum used for long-range radio (shortwaves and VHF frequencies).

Often, east-west communications are completely blocked while north-south communications continue unaffected. It’s another geophysical mystery why this is so.

The blockage usually lasts for 24 hours or less and the airwaves return to normal after everything settles down. Blockages can be a minor annoyance or a major problem, depending on how much of the spectrum is affected and what services use those frequencies.

Ham radio operators may want to take a night off, perhaps drive out of town to see if they can catch a view of the aurora.

If you miss it, there are videos of aurora displays all over the internet.