Through gravitational compression, earth layers were formed by process called density stratification. this process describe the layer of water in a body of water with a layer of cold dense water at the bottom were the temperatures are above freezing point, A water layer float on top and when the water on the surface coll to about 4 degrees it sinks
Push factors are factors that make people want to leave their environment they are living in, while pull factors are factors that attract people to an environment. Examples of push factors are famine/drought, and war, and pull factors are good living conditions, good jobs, good education
Tectonic theory is ur answer
between Europe and Asia (dividing Eurasia): along the Turkish Straits, the Caucasus and the Urals (historically also north of the Caucasus, along the Kuma–Manych Depression or along the Don River) between Asia and Africa (dividing Afro-Eurasia into Africa and Eurasia): at the Isthmus of Suez.
