[Slewfoot]

In the Himalayas there are limestone deposits over 20,000ft above current sea level. Limestone that formed on the bottom of an ocean. Either the mountains have been rising or the oceans were alot deeper in the past.

[cogitator]

Either the mountains have been rising

That's what happened with the Himalayas. The subcontinent of India plowed into Asia a few million years ago, and the Himalayan uplift resulted.