Difference between clast supported and matrix supported in alluvium?

Question

Does anyone know i have an exam in 2 hours and i dont know!

Answer 1

Clast supported means the clasts in the sediment i.e. pebbles, rocks, boulders etc. are touching each other. If you were to take out the clay, silt and sand between the cobbles, they'd remain in place.

In a matrix supported deposit, the majority of the outcrop is silt, sand or clay. If you remove the fine grained fraction in a matrix supported rock, the less common larger rocks would fall to the ground.