The United States of America is known for its vast and dynamic variety of eye-catching landscapes. This is because the country is about 2,680 miles running east to west and 1,583 miles north to south. That’s a lot of land with a lot of geological history, but you can find a surprising amount of variety in just a single state. So what does the geology of West Virginia have to offer? Well, probably more than you think. Let’s start with a little history to show you how West Virginia came to be.
Nearly a billion years ago, the North American continent was one of several that slammed into one another to form a vast supercontinent called Rodina. This was the period of time during which the foundation of West Virginia’s crust formed. These collisions of such land masses caused a great deal of heat and pressure, which melted rock that was already there. Some of this material rocketed to the surface to form mountains, while some was thrust downward into the mantle of Earth. Mountains erode slowly over millions of years, exposing the rock that was once pushed upward. A great deal of granite, gneiss, and igneous rocks are abundant in the Blue Ridge Mountains today. It all began that long ago.
Once the continents that formed Rodina began to split apart again, a layer of basalt was deposited because of volcanic activity. We call this the Catoctin formation. Around 600 million years ago, this formation lay on top of the mountains and valleys that had been created earlier.
That we can learn so much about a single rock formation is one of the appeals of geology. The tectonic activity helps shuffle nutrients and minerals necessary for life to flourish, as it soon would. Far atop the Catoctin formation is a sedimentary layer of marine deposits and small stones. These formed about 500 million years ago as a small sea swallowed what is today the entire state of West Virginia. Some of these rocks can still be found in deeper wells. Before the state finally rose above sea level just over 300 million years ago, the small layer of water left the Greenbrier Formation–limestone.
Even after the sea was gone, West Virginia had transformed into a massive swamp. During this period, massive deposits of sandstone and shale resulted. The Appalachian Mountains begin to form around 250 million years ago, and in fact most of the land within the state’s borders was slowly thrust skyward. As usual, when you have mountains you’re left with a period of erosion.
Unfortunately, the Mesozoic Era that ran from 225 to 66 million years ago didn’t leave any sedimentary rocks in West Virginia. This layer is where most dinosaur fossils are found around the world, but none were preserved here. There was volcanic activity in the areas surrounding the state, and up until only 100,000 years ago, glaciers covered the area. When they melted, lakes and rivers formed.