The Record of the Rocks

The Record of the Rocks

The Record of the Rocks are the Earth's diary. Layers of material, consisting of dirt, silt and dead and decaying animal life, gradually build up. The combined weight of these layers compresses the lower layers and, over millions of years, sedimentary rock is formed. The sedimentary layers are easily visible in situations where rivers have carved paths through relatively soft rock. The study of these layers provides valuable clues about how life and the environment have changed. [NS] {NR}