PPT Slide
Notes:
As the layers built up, they began to compress and harden from the weight and turned into a sedimentary rock called shale. Because of the very thin layers, the rock is called a paper shale. Each layer represents a volcanic eruption or a period of sediment deposition on the bottom of the lake. The plants and insects gradually disintegrated, but the carbon in their bodies, the building blocks of their cells, stayed behind to leave a carbon fossil imprint.