Just below the surface of Manassas National Battlefield lie the remnants of a history dating as far back as 200 Million years ago, a time when Pangea was breaking apart and dinosaurs were roaming the earth. Similar to how archaeologists use artifacts and written history to piece together the first and second battle of Manassas, geologists use rocks and fossils to try and understand the history of Earth. Each rock type (sedimentary, metamorphic, and igneous) provides a different perspective on how the world around us came to be.
The geologic history of Manassas National Battlefield Park is a history of active plate tectonics, continental rifting, and depositional basins. Over 200 Million years ago all of the continents had collided and formed the super continent Pangea. At the dawn of the Jurassic period, though, rifting began to occur, tearing Africa and North America away from each other. As these continents pulled apart the continental crust of Eastern North America began to thin and eventually started to crack. These cracks in turn acted like fault planes causing the land to sink down and form basins.