What is cryoclastism?

What are the geographical processes that shape deserts?

sands are the result of a process called cryoclastism. this process is based on water infiltration within rocks, and big differences between day and night temperatures. simplified, water infiltrates in rocks during day-time, the freezes over the night, which causes it to dilate and break the rock from within, in smaller pieces. this process goes on until rocks get smaller and smaller to small particules of what sand comproses of. then, winds generate most of the geomorphological forms found in deserts e.g. dunes.