CORRELATION Matching Rock layers in one place to another to see if they formed at the same time Can see continuity

CORRELATION “Walking the Outcrop” / Rock layer properties – observing rock layers for great distances, looking for the same color, texture, mineral composition of the rock layers

CORRELATION 2. Volcanic Ash – Huge eruptions leave an distinctive thin layer of ash over a very large area Good time marker

CORRELATION 3. Index Fossils – Found in large areas but lived for a short period of time Most Reliable correlation method Used to date rock layers

Which is the best index fossil? Trilobite – only found in one layer

Practice Questions The following questions pertain to Figure 1 What rock layer is oldest? Which is older the fault or the igneous intrusion? Describe the geologic history of this outcrop?

What rock layer(s) is the oldest? What is the name of the rock layer represented by layer E? What occurred between layers B and C? What is the name of the fossil in layers C and F? What time period was layer F deposited? Place the layers in order from oldest to youngest.