GENERAL GEOLOGY

Detailed explanation-1: -Summary. Question: The earth’s interior is composed of three main concentric zones: the crust, the mantle, and the core. The outermost layer, the crust, averages 40 km thick on the continents and is thinner (averaging 8 km thick) under the oceans.

Detailed explanation-2: -Models of Urban Structure Sociologists, economists, and geographers have developed three models to help explain where different types of people tend to live in an urban area – the concentric zone, sector, and multiple nuclei models.

Detailed explanation-3: -The Concentric Circle Theory claims that ideas start with Great Thinkers and that those ideas are then spread throughout the population in circles, much like the ripple effect you see in water when a rock is thrown in.

Detailed explanation-4: -The concentric zone model, also known as the Burgess model or the CCD model, is one of the earliest theoretical models to explain urban social structures. It was created by sociologist Ernest Burgess in 1925.