Describe how regional metamorphism of shale produces a sequence of rocks and minerals.

Metamorphism is a process by which preexisting rocks can be altered in composition or structure, to form a new rock. Regional metamorphism occurs in areas of above average pressures and temperatures, such as subduction zones. Shale is a sedimentary rock, which has a varied chemical composition, and it contains platy clay minerals that can align to pressure (associated with regional metamorphism).


Low-grade metamorphism (low pressure and temperature) of shale forms slate. Distinguishable by platy cleavage, where mica crystals align perpendicularly to pressure as well as the index mineral Biotite.


Medium-grade metamorphism (medium pressure and temperature) of shale forms schist. Schist is distinguishable by the index minerals Kyanite and/or Garnet, it may also show slight banding of dark/light minerals.


High-grade metamorphism (high pressure and temperature) of shale forms Gneiss. Gneiss shows very distinct banding between light and dark minerals, which have separated due to different compositions and has the index mineral Sillimanite.


It is important to point out that index minerals show the minimums pressure and temperatures the shale must have experienced. A metamorphosed shale may contain Biotite and Garnet (two minerals formed at different P+T), this shows that metamorphosed shale must have at least experienced medium grade metamorphism.

Josh S. A Level Geology tutor, GCSE Geology tutor, GCSE Geography tut...

2 years ago

Answered by Josh, an A Level Geology tutor with MyTutor

Still stuck? Get one-to-one help from a personally interviewed subject specialist


£22 /hr

Daniel V.

Degree: Earth Sciences (Bachelors) - Durham University

Subjects offered:Geology, Geography+ 2 more

-Personal Statements-

“Geology at Durham. Exams were very stressful. Run charity society. Footballer. Teach in different styles, recaps. Keywords stuck everywhere. ”

PremiumOliver B. GCSE Chemistry tutor, GCSE Biology tutor, GCSE Geology tuto...
£36 /hr

Oliver B.

Degree: Medicine (PhD) (Doctorate) - Bristol University

Subjects offered:Geology, Science+ 5 more

Extended Project Qualification
-Personal Statements-

“I have been teaching here for over 2 years and am willing to go the extra mile for any regular pupil of mine. I use varying teaching styles depending on what helps you to learn best!”

£20 /hr

Alfie B.

Degree: Earth Sciences (Bachelors) - Oxford, St Anne's College University

Subjects offered:Geology, Physics+ 1 more


“Hello! I am an undergraduate student at the University of Oxford and am very enthusiastic and passionate about science and maths.”

MyTutor guarantee

About the author

£22 /hr

Josh S.

Degree: Earth Sciences (Masters) - Durham University

Subjects offered:Geology, Physics+ 2 more


“Hello, I'm Josh. I'm an undergraduate, currently in my third year, studying Earth Sciences (Geology) at Durham University.”

You may also like...

Other A Level Geology questions

Explain how Earthquakes Occur when Stress Stored in Rocks is Released.

Which tectonic settings experience earthquakes?

Describe the Difference Between ‘Faults’ and ‘Joints’ in Rocks.

Why is heat flow over a mid-ocean ridge higher than over an oceanic trench?

View A Level Geology tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss