The marine Tertiary accumulations commence with those that are referable to the Eocene series, consisting of nummulitic limestones, marls and siliceous sandstones.
As the period advanced, along the very line that had been occupied by the nummulitic sea (Tethys) the crust began to be folded up, giving rise to the Alps, Carpathians, Caucasus, Himalayas and other mountains, some of the early Tertiary marine formations being now found raised more than 16,000 ft.
In northern Africa they are well developed and of much interest._ They contain the well-known nummulitic limestone of Eocene age, which has been traced from Egypt across Asia to China.
The mass of the mountain is composed of nummulitic limestone.
The Spiti shales are succeeded conformably by Cretaceous beds (Gieumal sandstone below and Chikkim limestone above), and these are followed without a break by Nummulitic beds of Eocene age, much disturbed and altered by intrusions of gabbro and syenite.