Kober not only attempted to explain the origin of mountains on the basis of his Geosynclinal Theory but he also attempted to elaborate the various aspects of mountain building, e.g. formation of mountains, their geological history and evolution and development. Kober's Geosynclinal Theory is based on the forces of the contraction produced by the cooling of the Earth. The force of contraction generated due to cooling of the rigid masses or forelands which squeeze buckle and fold the sediments into mountain ranges. According to Kober, there were mobile zones of water in the places of present day mountains. He called those mobile zones of water as geosynclines or Orogen. The mobile zones of geocyncline were surrounded by rigid masses which were termed by Kober as 'Kratogen'.
Consider the following statements about Kober's Geosynclinal Theory:
I. It attributes the origin of mountains primarily to the erosional activities of rivers.
II. The theory suggests that mountain building involves a sequence of lithogenesis, orogenesis, and gliptogenesis stages.
III. Geosynclines, according to Kober, are surrounded by rigid areas known as Kratogen.
Which of the above statements are correct?