A dirt road or track is a type of unpaved road not paved with asphalt, concrete, brick, or stone;[1] made from the native material of the land surface through which it passes, known to highway engineers as subgrade material.
This leads to greater waterlogging and erosion, and after heavy rain the road may be impassable even to off-road vehicles.
[citation needed] Dirt roads take on different characteristics according to the soils and geology where they pass, and may be sandy, stony, rocky or have a bare earth surface, which could be extremely muddy and slippery when wet, and baked hard when dry.
[citation needed] Dirt roads almost always form a washboard-like surface with ridges.
It is as easy to become bogged in sand as it is in mud; a high clearance under the vehicle may be required for rocky sections.