Originally Posted by downunder
"self compress" ??????????????
Maybe in Oregon, but not in Georgia red clay in the last 55 years. I doubt in Virginia as well.
Gotta wonder how that is different from just normal settling.
"to press or squeeze together; force into less space.
Webster's College Dictionary, Random House, New York, 1991
Water erodes clay and carries it downward to voids in the soil. There is settles and of course hardens and the water leaches away. The process repeats itself over and over till there is no more void.
Soon there is no water that will penetrate the soil. Water just sits on the top of the clay and rots the roots, unless of course the plants are the type that like lots of stagnant water.
Clay is clay.
Many of the structures in the 1800's in the SW are made from clay, sand water and baked into bricks in the sun. It's called adobe and is pretty hard when dried out.
I guess compress is not the right word since it is already pretty hard.
Eventually it will compress to the point of being rock. It's called sedimentary rock and one of the three major types of rock (the other two being igneous and metamorphic).
New Orleans is built on clay and will keep sinking until it becomes rock. Water is the key to this compression which aids in getting the voids out and makes the material denser.