Q. With reference to various geographical phenomena, consider the following statements:

1. A doline is a depression on land formed by collapse of the surface layer.
2. A bluehole is a marine version of a sinkhole.
3. Caldera is a hollow depression under volcanic landscapes.
4. Gully is an erosional landform created by running water.

Which of the above statements is / are correct?
Answer: 1, 2, 3 and 4
Notes: A doline is a surface depression created by collapse, common in karst landscapes. Blueholes, like those found in the Bahamas, are underwater sinkholes. Calderas are large volcanic depressions formed after magma chamber collapse. Gullies result from water erosion forming channels, especially on slopes, making all four statements correct.