Answer: Tethys Sea
Notes: During the Geologic period, the Ganges plain was an ocean. It was known as Tethys Sea. The Ramnagar Doon and Someshwar range are situated in the north-western part of Bihar and are part of the outer Himalaya or Shivalik range which was formed at the end of the Tertiary period. It is made up of sandstone and conglomerate.
