answer:
■ In the early days of Archaic times (4 billion years ago to 2.5 billion years ago), magma activity was intense, volcanic eruptions were frequent, and some primitive land cores were formed. ■ Later, it gradually expanded into a primordial land crust, at which time the surface of the earth was almost completely covered by the ocean. ■ By the late Archaic period, small-scale land formations formed in some areas due to multiple tectonic movements.
■ In the early Proterozoic period (2.5 billion years ago to 541 million years ago), volcanic activity was still quite frequent, the earth's crust was moving violently, the surface ups and downs increased, and the land scale continued to expand. ■ In the later period, a number of stable ancient lands were formed.
○ What do you say about the precambrian sea and land changes?
![【Marine Scientific Expedition】5 days and 4 nights•Sea and land linkage Xisha Islands•[North Reef] sea area scientific investigation[fig]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)