Transcript Metamorphic Rocks

Metamorphic Rocks
D. Crowley, 2008
Tuesday, April 5, 2016
Metamorphic Rocks
To know how metamorphic rocks are formed
Rocks
What are the 3 types of rock?
1. Sedimentary
2. Igneous
3. Metamorphic
•
Sedimentary – rocks with rounded grains in layers
•
Igneous – randomly arranged interlocking crystals
•
Metamorphic rocks…
Metamorphic Rocks
• Metamorphic rocks are formed from existing sedimentary rocks
that are changed because of heat or pressure
• Earth movements may cause rocks to be deeply buried or
squeezed - these rocks are heated and put under great pressure
but they do not melt (if they melt they become igneous rocks)
• The minerals they contain are changed chemically, forming
metamorphic rocks
Formation
• Compare the following metamorphic rocks from the sedimentary
rock they formed from (we know what sedimentary rock they
formed from as they have the same chemical composition)…
Limestone
(with bivalve fossils)
Marble
Metamorphic Rocks
• Marble is formed from limestone
• Very high temperatures break down the shells and they form small
crystals (but the rock does not melt)
Limestone
Marble
Metamorphic Rocks
• Slate is formed from clay
• As the clay gets heated and compressed the tiny plate-like
particles align in the same direction (split into sheets, great for
roofing material)
Clay
Slate
Metamorphic Rocks
• Schist is formed from mudstone due to huge temperatures
(mudstone can become slate if there is high pressure but not high
temperature)
• New minerals such as mica form due to the huge temperatures
creating layers (needs steady heat and pressure)
Mudstone
Schist
Metamorphic Example
Metamorphic
• Complete the metamorphic
rocks worksheet
Metamorphic