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EnglandGeologyQuick questions
Rock deformation and geological structures
Quick questions on Geological maps and cross-sections: outcrop patterns, cross-sections and the order of events - Eduqas A-Level Geology
6short 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 reading outcrop patterns?Show answer
A geological map shows where each rock unit reaches the surface (its outcrop), and the pattern reveals the structure:
What is the younging direction?Show answer
The younging direction is the direction in which the beds get younger. By the principle of superposition, in an undisturbed sequence the beds young upwards, so on a tilted sequence they young in the direction of dip towards the top of the pile. You confirm it with way-up (geopetal) evidence (graded bedding, cross-bedding, ripple marks, desiccation cracks, fossils in life position), which is essential where folding may have overturned the beds and the simple "younger on top" rule could be reversed.
What is constructing a cross-section?Show answer
To draw a cross-section along a line on the map:
What is q1?Show answer
State what the outcrop of a horizontal bed does relative to the topographic contours. [1 mark]
What is q2?Show answer
On given topography, what does a wide outcrop of a bed indicate about its dip, and what does a narrow outcrop indicate? [2 marks]
What is q3?Show answer
Name the principle that tells you an intrusion is younger than the rocks it cuts, and the principle that tells you a pebble is older than the conglomerate containing it. [2 marks]
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