Back to the full dot-point answer
WalesGeologyQuick questions
F3: Time and Change
Quick questions on Relative dating and stratigraphic principles - WJEC 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 are combining the principles?Show answer
Real sequences need several principles together. A granite that contains fragments of the country rock (so the country rock is older), is cut by a later dyke (so the dyke is younger), and is overlain across an unconformity by sediments (so those sediments are younger still) can be fully ordered only by using inclusions, cross-cutting and the unconformity in turn.
What is hutton's unconformity at Siccar Point?Show answer
James Hutton recognised gently dipping Old Red Sandstone resting on near-vertical greywackes, reading deposition, tilting, erosion and renewed deposition from one outcrop, the founding example of deep time. Dating an intrusion against a fault. A mineralised vein cut by a fault is older than the fault, so a prospector knows the faulting post-dates and may offset the ore, a practical use of cross-cutting. Conglomerate provenance. Rounded pebbles of older rock within a conglomerate prove a source terrain was eroding before the conglomerate formed, using the inclusion principle to reconstruct landscape history.
What is q1?Show answer
State the principle of superposition and the condition under which it holds. [2 marks]
What is q2?Show answer
A dyke cuts through three sedimentary beds. Is the dyke older or younger than the beds, and which principle tells you? [2 marks]
What is q3?Show answer
Name the three types of unconformity. [3 marks]
Have a question we have not covered?
This dot-point answer is short enough that we have not extracted many short questions yet. Read the full dot-point answer or ask Mo, our study assistant, in the chat for follow ups.