Describe The Formation Of Metamorphic Rocks

Question 1

Describe the formation of 2 metamorphic rocks you have studied
Intro

Answer 1

• Metamorphic rocks are formed from igneous or sedimentary rocks that have been changed as a result of heat and or pressure
• There are 2 types of metamorphism Contact (thermal) and regional
• Contact metamorphism occurs when there is an intrusion of molten magma in the crust and as a result the rocks are changed by heat alone, this is localised as it only heats the band of surrounding rock
• Regional metamorphism occurs when heat and pressure are applied over a large area, rocks are exposed to extreme pressure from surrounding plates colliding and high temperatures due to magma rising through buckled rock
• The two metamorphic rocks i will be mentioning is Marble and Quartzite

Question 2

Paragraph 1

Answer 2

-Marble is a coarse grained rock whose parent rock is either limestone or chalk

-Most marble was formed as a result of regional metamorphism where the limestone is changed by both pressure and heat.
The structure of the limestone is destroyed as fossils and other organic material trapped in the limestone is broken down, crystals are melted by the heat and are reformed as larger crystals in the new marble

• The Limestone that marble is formed from often contains impurities which gives the marble colour, presence of iron oxide produces pink marble, while serpentine produces green marble
• Marble is found in many locations in Ireland, Green marble is found in Connemara, Red marble found in Cork and White marble found in Rathlin Island
• Used in statues and as building materials

Question 3

Paragraph 2

Answer 3

• Quartzite is made from its parent rock, sandstone that has been metamorphosed, the change occurred in periods of folding when sandstone came in contact with deeply buried magma
• Extreme heat and pressure caused the quartz and silica grains in the sandstone to melt and destroyed the stratified structure of the sandstone, material cools and fuses together creating a new rock with larger grains

-Quartzite varies in colour, depending on the impurities in the original rock
It is a non porous rock much harder than its parent rock

-Quartzite is extremely resistant to weathering and erosion, can be found in Craogh Patrick Co Mayo and Sugar Loaf Co Wicklow

Question 4

Diagram

Answer 4