Massive Igneous Rock

Question 1

Identify 5 igneous intrusion

Answer 1

Batholiths, Laccoliths, sills, dykes, lopoliths

Question 2

briefly explain all the igneous intrusions

Answer 2

1) Batholiths- Granite. Large dome-shaped intrusion. cools beneath the earth’s surface.
2) Laccoliths- Dolerite. These are mushroom-shaped intrusions. The magma intrudes between the layers of rocks and pushes overlying sedimentary rock upwards.
3) Lopoliths- Granite. saucer-shaped intrusions. The sedimentary rock below will bend downwards
4) Dykes- Dolerite. Vertical sheets of magma
5) Sills- Dolerite. Magma intrudes between bedding planes (horizontally). Regarded as stratified

Question 3

What is the difference between contractual and off-loading joints

Answer 3

Contractual joints form from the cooling and contraction of magma. These cracks are at right angles while off-loading joints occur when overlying weathered material is eroded. The release from the pressure causes cracks

Question 4

What is a granite dome

Answer 4

A granite dome is a batholith that has been exposed due to erosion of overlying strata

Question 5

What is exfoliation and explain how it happens

Answer 5

Exfoliation is layers of rock peeling off due to expansion and contraction. Off-loading joints cause the rock to have layers and when the rock continuously expanded(heated) and contracts(cools)

Question 6

What are Tors

Answer 6

Tors are exposed granite core stones. It is surrounded by weathered material and bottom core stones are linked to bedrock

Question 7

what are core stones

Answer 7

Granite boulders left after rock surrounding it is removed,

Question 8

Explain the theory of how Tors formed.

Answer 8

1. Rock is chemically weathered along the joints while it’s underground.
2. When granite is exposed, the weathered material is removed.
3. joints are far apart to create tors
4. Rate of erosion > than rate of chemical weathering