Sedimentary Rocks

Lab 5:Reading Earth's history from rocks

Grand Canyon, AZ

photo: M.J. Soreghan

Sedimentary rocks, because they form at the Earth's surface, form an amazing diary of the Earth's past. Each layer records an old landscape: A desert, a shallow sea, a large river. Geologists study these sedimentary layers in order to reconstruct ancient landscapes and, in turn, determine how these landscapes changed over time. Maps of old landscapes are called paleogeographic maps.

In the lab exercise this week, you will use sedimentary rocks to reconstruct an ancient landscape and attempt to predict the location of a an ancient delta that now forms a reservoir for petroleum.

Sedimentary rocks also are the primary data for understanding future climate change. Because sedimentary rocks can be such faithful recorders of past climate, we can use the record of past climate change to predict natural variations in future climate. This natural climate variation can then be factored into climate models that predict potential climate change caused by human impacts such as burning of fossil fuels and deforestation.

One example of using sediments to infer past climate comes from East Africa. The links in the menu shows how lake sediments form a high resolution record of past climate change and how climate change has impacted one part of Africa: The Sahel.

What to do:

Prior to coming to lab, study the information provided under the menu (above left).