Whiteboard: Relative Dating and Sedimentary Environments
Using your knowledge of the principle of superposition, describe or draw on the whiteboard below to explain the relative age of the layers in the formation. It is not important that you label each rock layer, but simply indicate what layer is youngest and oldest and indicate the progression through time. Once you are confident of your answer, click on the check answer link below.
Check Answer
The bottom layer is the oldest, and the layers get progressively younger toward the top. Since shale is a finer-grained sedimentary rock than sandstone, the Mancos Shale was deposited in an off-shore environment; the Point Lookout Sandstone was deposited in a near-shore environment.
