Lesson
Presentation
Discovering the history of sediments
Layers of sedimentary rocks are called strata. Think about a pile of books or papers lying on a table.
- Which one was put down first?
- Which one was put down last?
- What does this suggest about the relative ages of the layers in a sequence of strata?
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A
fundamental "rule" of stratigraphy (the study of strata) is that in any
undisturbed pile of strata the youngest will be at the top and the oldest
will be at the bottom. This is known as the Princple
of Superposition, and provides the key to developing a geologic
history from studying a sequence of sediments.
