Here's why:
* High Surface Area: Clay particles are incredibly small and have a very high surface area to volume ratio. This means there's a lot of space between particles where water can be trapped.
* Weak Bonds: Clay minerals are held together by weak chemical bonds. These bonds are easily broken by pressure.
* Water Expulsion: As the weight of overlying sediments increases, the water trapped between clay particles is squeezed out. This process reduces the pore space significantly, leading to greater compaction.
Other sediments and their compaction:
* Sand: Sand grains are larger and have less surface area than clay. They experience less compaction.
* Gravel: Gravel is the least compressible sediment due to its large size and relatively small surface area.
In summary: Clay's small particle size, high surface area, and weak bonding make it the most prone to compaction during the lithification process.
