aped ▁is ost atic ▁de pression , ▁in ▁which ▁the ▁material ▁has ▁begun ▁to ▁slide ▁down hill . ▁In ▁some ▁cases , ▁the ▁sl ump ▁is ▁caused ▁by ▁water ▁beneath ▁the ▁slope ▁weak ening ▁it . ▁In ▁many ▁cases ▁it ▁is ▁simply ▁the ▁result ▁of ▁poor ▁engineering ▁along ▁high ways ▁where ▁it ▁is ▁a ▁regular ▁occurrence . ▁ ▁Sur face ▁cre ep ▁is ▁the ▁slow ▁movement ▁of ▁soil ▁and ▁rock ▁de br is ▁by ▁gravity ▁which ▁is ▁usually ▁not ▁per cept ible ▁except ▁through ▁extended ▁observation . ▁However , ▁the ▁term ▁can ▁also ▁describe ▁the ▁rolling ▁of ▁dis l od ged ▁soil ▁particles ▁ ▁in ▁diameter ▁by ▁wind ▁along ▁the ▁soil ▁surface . ▁ ▁Fact ors ▁affect ing ▁soil ▁er os ion ▁ ▁Cl imate ▁The ▁amount ▁and ▁intensity ▁of ▁precip itation ▁is ▁the ▁main ▁clim atic ▁factor ▁gover ning ▁soil ▁er os ion ▁by ▁water . ▁The ▁relationship ▁is ▁particularly ▁strong ▁if ▁heavy ▁ra inf all ▁occurs ▁at ▁times ▁when , ▁or ▁in ▁locations ▁where , ▁the ▁soil ' s ▁surface ▁is ▁not ▁well ▁protected ▁by ▁veget ation . ▁This ▁might ▁be ▁during ▁periods ▁when ▁agricult ural ▁activities ▁leave ▁the ▁soil ▁bare , ▁or ▁in ▁semi - ar id ▁regions ▁where ▁veget ation ▁is ▁naturally ▁sparse . ▁Wind ▁er os ion ▁requires ▁strong ▁wind s , ▁particularly ▁during ▁times ▁of ▁dr ought ▁when ▁veget ation ▁is ▁sparse ▁and ▁soil ▁is ▁dry ▁( and ▁so ▁is ▁more ▁er od ible ). ▁Other ▁clim atic ▁factors ▁such ▁as ▁average ▁temperature ▁and ▁temperature ▁range ▁may