Question

Consider the following pairs: Which of the pairs given below are correctly matched ?

Lacolith	Dome shape
Lopolith	Irregular shape
Phacolith	Lens shape
Batholith	Saucer shape

• A. A-2, B-1, C-3, D-4
• B. A-1, B-4, C-3, D-2
• C. A-4, B-1, C-3, D-2
• D. A-4, B-2, C-3, D-1

Answer 1

Answer:

B. A-1, B-4, C-3, D-2

Intrusive igneous rocks are formed when magma solidifies beneath the Earth's surface. The shapes they form are based on their structure and are correctly described as follows:

1. Lacolith (Dome shape): A lacolith is a large, lens-shaped mass of magma that pushes the overlying rock layers into a dome-like shape.

2. Lopolith (Saucer shape): A lopolith is a large, saucer-shaped intrusion where the magma sinks into a basin-like structure.

3. Phacolith (Lens shape): A phacolith is a small, lens-shaped intrusion that occurs at the crest of an anticline or the trough of a syncline.

4. Batholith (Irregular shape): A batholith is a massive, irregular body of intrusive igneous rock. It is the largest of the intrusive rock forms and is often exposed only after erosion of the overlying material.