What did wilbur zelinsky's model of migration predict?

Wilbur Zelinsky's most previous job was a geography professor at Pennsylvania State University. Zelinsky's model proved five different phases for different types of society, shown here: (1) Premodern traditional society: very little migration (2) Early transitional society: high rate of migration from rural areas to cities (3) Late transitional society: urban to urban migration (4) Advanced society: urban to suburban migration (5) Future super advanced society: interurban migration.

Ba population changes in response to a change in environment

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.