In Gröf soil formation was seriously affected after AD 1362 with limited accumulation of soil organic matter and soil organic carbon as well as little clay formation but after AD 1477 a recovery is observed.
Í Gröf hafði gosið 1362 neikvæð áhrif á jarðvegsþróun með lítilli uppsöfnun lífræns efnis, lífræns kolefnis og leirsteinda en eftir gosið 1477 breyttist þróunin til hins betra að nýju.