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EnglandGeologyQuick questions
Module 2 and 4: Fossils and time; Interpreting the past
Quick questions on Relative dating and stratigraphic principles: superposition, cross-cutting and reconstructing a geological history - OCR A-Level Geology
5short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the principles of relative dating?Show answer
Relative dating puts geological events in order (which came first) without giving an actual age in years. The principles are:
What is way-up evidence?Show answer
In folded or overturned rocks the beds may be upside-down, so you need way-up (younging) evidence to tell which way is the original top. Useful indicators include graded bedding (coarse at the base, fine at the top), cross-bedding, ripple marks (crests point up) and desiccation cracks (wider at the top). These tell you the original top of the bed and so the correct order.
What is q1?Show answer
State the principle of superposition. [1 mark]
What is q2?Show answer
A dyke cuts a series of sandstone beds. State whether the dyke is older or younger than the sandstones and why. [2 marks]
What is q3?Show answer
Explain how graded bedding can be used as way-up evidence. [2 marks]
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