Question

Give reasons as to why Sea caves turn into stacks.

Answer 1

Hint:
> Sea caves and stacks are both erosional landscape features.
> The structure of both the sea caves and sea stacks hold a clue to how they are formed.
> They are both features of coastal geomorphology.

Complete answer:
In order to understand how sea caves are turned to stacks, we need to first know what they are. Below is a brief definition of the terms-

Sea caves are cave-like structures found in most parts of the world along with the coastal areas that have cliffs or rocks. They are formed due to erosion of the rock/cliff faces by the continuous action of the water. Sea stacks or simply stacks are the steep vertical columns of rocks in the sea near the coastal areas. These are formed due to erosional activity of both the water and the wind.

Sea caves are formed when repeated action of the waves of water erode away the rocks forming hollow areas. These hollows eventually get big enough to form cave-like structures, hence the name ‘sea caves’. The water further works on these caves causing the walls to erode away, leaving only the roofs intact. This eventually forms columns of rocks with an arch connecting them overhead where the action of the water is the least. These exposed arches then are broken due to erosional activity of the wind as well the weathering due to thermal effect. When the arches breakaway, only the resulting columns of hard residual rocks are left standing, forming the structure that we know as stacks.

The process of sea caves or arches forming stacks is made faster by the effects of earthquakes or very strong waves.

Note:
> Sea caves and arches can be formed of all types of rocks- sedimentary, igneous and metamorphic.
> Some famous sea caves are- Benagil Beach sea cave in Portugal, Sea Lion caves in Florence, Admiral’s arch in Australia, and Phang Nga Bay caves in Thailand.
> Some famous sea stacks are- Lange Anna in Germany, Totem Pole in Australia, Apostles is Australia, Old Man of Hoy in Scotland and Haystack Rock in the USA.
> Sea caves, arches and stacks are erosional features of coastal areas whereas sandy beaches are depositional features.