The largest glacier of the Petuniabukta area is the Hörbyebreen. It is among the tew on Spitsbergen whose marginal zones undergo areal decay. What has made in this type of glacier is a rich supra-glacial moraine cover that was formed as a result of a deformation of debris bands in the frontal part following a surge. In the marginal zone three subzones were distinguished differing in the degree of degradation of passive ice that covers almost all its area. They also differ in the stability of deposits and in the relief.