About Road Maintenance Pavement deteriorates from the bottom up. This means that the thin new crack seen on the surface is actually the end of a wider crack deep in the road foundation.
Potholes are the product of unrepaired cracks.
The gravel fills with dirt and water that does not move like the asphalt. When the temperature drops the block of dirt and gravel can't shrink so it pops out, leaving the loose material to be scattered by traffic. Now the pothole grows as vehicle wheels drive into it and knock more asphalt away from the road surface.