Formation of the Appalachian
mountains present a fascinating portrait drawn from geologic
time. The story is one of massive
continental plates - North American and North African, crashing
into each other forming the Appalachian Mountians. In times
the two tectonic plates separted as the Atlantic Ocean widened.
For an explanation see http://www.geo.utep.edu/...
The original Appalachia.
More than half a billion years ago there was no North
American continent as we know it. Rather, along what
is now the Atlantic seacoast was a land called Appalachia.
West of it was a huge sea with a narrow trough which
extended along the same belt as is occupied by today's Appalachian
Trough. The trough,
which lasted 400 million years, was a repository for sediments
from the rivers which flowed down the west side of Appalachia.
Through time (Paleozoic Era) the trough would fill with
sediments then sink from the weight and repeat the process
again and again, ultimately establishing a multi-layered
deposition more than 50,000 feet thick. These sediments
were compacted into thousands of individual beds of rocks
resting at the bottom of a sea; hence the term "sedimentary
Among these sediments, starting in the era's Devonian period
commencing 410 million years ago, was decaying organic matter
from forests. Later, in the Pennsylvanian Period
which began 330 million years ago when the trough was full
of sediments, vast swamplands near sea level dominated the
Plants. Coal swamps
contained a wealth of plant life now extinct. Giant
ferns up to 50 feet in height paired with 100-feet-tall
lycopods, or scale trees, whose distinctive fossils can
be found in eroded creek beds on occasion or during coal
mining. In fact, seams of coal can be identified by microscopically
examining fossil spores contained in layers of rock. These
plants would die, turn into peat, be compacted twenty-fold,
and become coal. To learn more about the coal-forming
process you can access http://www.uky.edu/...
Thus, the Pennsylvania Period became known as the Great
Coal Age. Important oil and gas deposits originate from
this time period, too.
Mountains form. At
the end of the Paleozoic Era, during the Permian Period
which began 275 million years ago, there was tremendous
mountain-building throughout the planet including Appalachia.
Great pressures buckled the sedimentary beds of rock
upward from the sea bottom and the Appalachian Mountains
came into being (as did the Great Plains region).
Their height may have been as tall as the highest Alaskan
mountains are today. West Virginia has not been under a
sea since then.
The next era, the Mesozoic, is familiar to most people.
Its' three periods -- Triassic, Jurassic, and Cretaceous,
spanning 220 million to 70 million years ago, is known
for the Age of Reptiles, specifically dinosaurs.
Mammals appeared. The tall Appalachian Mountains slowly
eroded by action of the many streams which flowed down from
them. Ultimately these mountains were worn down
into a giant plain known as a peneplain and it has
been called the Appalachian Peneplain.
Uplift. In the Cretaceous
Period this peneplain was gently uplifted again to a great
plateau during the same time the Rocky Mountains were formed.
The Appalachians were not elevated evenly, though.
Like a tilted table, the eastern part was
raised the most and so the mountains to this day slant downward
toward the west. The lowest portion (west) tips
toward the Mississippi Valley and the highest area (east)
became the present day Smoky Mountains and Blue Ridge Mountains.
Valleys form. Also
lifted were the rivers of the peneplain which, once elevated,
carved steep valleys and canyons into the plateau
which was the remnant of the original Appalachian Mountains.
These flat and narrow tops of the Appalachian Peneplain
are what we can see in the distance from a viewing position
on the state's highest peaks. More information on
West Virginia's geologic history can be found at http://www.wvgs.wvnet.edu/...
You can view a color geologic
map of West Virginia at http://www.wvgs.wvnet.edu/...
Last updated on Wednesday, August 22, 2001