ally ▁been ▁seen ▁as ▁re lict ▁land forms ▁from ▁past ▁times ▁when ▁these ▁areas ▁were ▁under ▁per ig la ci ation . ▁ ▁The ▁term ▁" f elsen me er " ▁comes ▁from ▁the ▁German ▁meaning ▁' se a ▁of ▁rock '. ▁In ▁a ▁f elsen me er ▁or ▁block field , ▁free ze - th aw ▁weather ing ▁has ▁broken ▁up ▁the ▁top ▁layer ▁of ▁the ▁rock , ▁covering ▁the ▁underlying ▁rock ▁formation ▁with ▁j ag ged , ▁angular ▁b ould ers . ▁Free ze - th aw ▁or ▁fro st ▁weather ing ▁occurs ▁when ▁water ▁that ▁is ▁tra pped ▁along ▁micro cra cks ▁in ▁rock ▁exp ands ▁and ▁contract s ▁due ▁to ▁fl uct u ations ▁in ▁temperature ▁above ▁and ▁below ▁the ▁free zing ▁point . ▁F elsen me ers ▁are ▁formed ▁in ▁situ , ▁meaning ▁that ▁they ▁are ▁not ▁transport ed ▁during ▁or ▁after ▁their ▁creation . ▁ ▁Character istics ▁ ▁Sur face ▁F elsen me ers ▁only ▁form ▁on ▁s lop es ▁of ▁ 2 5 ° ▁or ▁lower . ▁A ▁ste eper ▁angle ▁results ▁in ▁transport ▁of ▁the ▁blocks ▁due ▁to ▁gravity . ▁This ▁creates ▁a ▁tal us ▁slope , ▁rather ▁than ▁a ▁f elsen me er . ▁Cru de ▁sorting ▁with ▁b ould er ▁im br ic ation ▁can ▁occasionally ▁be ▁seen ▁on ▁the ▁surface ▁of ▁f elsen me ers . ▁ ▁Profile ▁The ▁depth ▁of ▁the ▁b ould er ▁field ▁depends ▁on ▁the ▁slope ▁angle , ▁rock ▁types , ▁age , ▁and ▁er os ional ▁history