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EnglandGeologyQuick questions
Module 2: Foundations in geology - Minerals and rocks
Quick questions on Metamorphic processes and grade: regional, contact and dynamic metamorphism, foliation and index minerals - 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 foliation?Show answer
Foliation is the parallel alignment of platy or elongate minerals (for example mica), produced by directed pressure, which rotates and grows the minerals at right angles to the maximum stress. Foliation is therefore the signature of regional (and dynamic) metamorphism and is absent in contact metamorphism, where pressure is not directed.
What are index minerals?Show answer
Index minerals are stable only within particular temperature and pressure ranges, so their presence marks the grade and lets geologists map metamorphic zones:
What is q1?Show answer
State the three agents of metamorphism. [2 marks]
What is q2?Show answer
Explain why regional metamorphism produces foliated rocks but contact metamorphism does not. [2 marks]
What is q3?Show answer
Place these rocks in order of increasing metamorphic grade: gneiss, slate, schist, phyllite. [2 marks]
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