how is shale formed?

Answer 1

Shale is formed from very fine particles of aluminosilicates (mud and clay). This only occurs in very low energy environments, such as deep ocean water.

Answer 2

When molten rock,or magma migrates upto the crust of the earth,it cools and solidifies.This is called igneous rock.When this igneous rocks undergo weathering and erosion,sediments are produced.These sediments are eventually carried out to sea and are collected in layers.These layers become increasingly deeply buried and compressed by the weight of overlying layers to form sedimentatry rock.One such sedimentary rock is shale.