Answer:
a huge depression
Explanation:
Mesa Verde is a place geologically famous for the 'alcove formation'. These alcoves are the depressions formed when water goes into the cracks, it gets freezed and due to freezing it exerts pressure on the surrounding, causing surrounding walls/rocks to move away or apart from each other. This the alcoves are formed. They are depressions similar to caves, but caves are formed underground.
Homo ergaster may have been the first human species to leave Africa and fossil remains show this species had expanded its range into southern Eurasia by 1.75 million years ago. Their descendents, Homo erectus, then spread eastward and were established in South East Asia by at least 1.6 million years ago.Oct 30, 2015
