Extensive floors of well-developed ancient trough-like valleys around Petuniabukta were subject to glacial, marine and alterations caused by gravity movements during the Late Pleistocene and Holocene. Palaeogeographical changes took place and are still occurring under the influence of land uplifting movements. The earliest recognizable phase of glaciation occured during the so called Billefjorden Stage about 35.000 to 45.000 years ago. The available evidence suggests that the glaciation was divided into two stages, first the major advance and then, a minor ice advance. This glacial episode was followed by morphological alterations conditioned largely by the action of sea and gravitational factors. About 6.500 years BP a short-term, though rather extensive glacier advance took place and afterwards, the processes of marine morphogenesis recurred. The last notable glaciation phase traced from the land surface can be identified with the Little Ice Age. The Holocene changes in morphology are reflected in extensive outwash plains and a tidal plain.
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.