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.