Multiple choice The deposits at the ancient Tethys sea were folded to form the Himalayas Rockies Andes Alps Reveal answer Fill a bubble to check yourself A Correct answer Explanation The Tethys Sea was an ancient ocean that existed between the Indian and Eurasian plates. As India moved northward and collided with Eurasia, the marine sediments of the Tethys were folded, faulted, and uplifted to form the Himalayan mountain range.