Boulders in a field tend to weather from beneath. Compressibility - tendency to consolidate, compress. Sand is low, clayey soils are High. Erodibility - tendency to erode by wind and water. Permeability - ease of flowing water through.
Soils erode, leaving hardened ground, lessening infiltration further.
Four wheeling can be very bad for certain areas. Runoff as much as 8 times faster than adjacent areas, sediment yield comparable to that of construction sites. Sometimes easier to just leave it there and buy the whole town, like Times Beach, Missouri. Dioxin was in the oil sprayed on the roads to keep down the dust, which was not a great idea. Dioxin is very poisonous.