What does gravity do ???

Asquirrel population lives in an area. over many years, a river in that area grows wider and stronger, eventually forming a canyon. the squirrel populations on the two sides of the canyon can no longer mate with each other and ultimately form distinct species. this is an example of

Which is a kingdom? protistachordataprokarya mammalia

Which of the following can be assumed about the layers in areas 2 and 4