21. practice: formation of mountains\nquestion 1\nwhat happens in the theory of isostasy?\ncheck my…

Brief Explanations:

Question 1: The theory of isostasy states that the Earth's crust 'floats' on the denser, more plastic - like mantle below. There is a state of gravitational equilibrium where the weight of the crustal columns (including mountains, plains, etc.) is balanced by the buoyant force exerted by the underlying mantle. Question 2: Buoyancy is the force that allows the Earth's crust to 'float' on the mantle, which is a key factor in isostatic equilibrium. Isostatic equilibrium is the state of balance between the weight of the crust and the buoyant force. Epeirogenic processes are large - scale, long - term uplift or subsidence of large areas of the Earth's crust. They are related because epeirogenic processes can disrupt isostatic equilibrium, and the principle of buoyancy is what drives the adjustment back towards equilibrium. Question 3: Block mountains form due to tensional forces in the Earth's crust. Faults develop, and large blocks of the crust are either uplifted or down - dropped. They typically form along tectonic plate boundaries or in areas of high tectonic activity, such as rift zones.

Answer:

Question 1: The Earth's crust floats on the mantle in a state of gravitational equilibrium. Question 2: Buoyancy enables crustal floating for isostatic equilibrium; epeirogenic processes can disrupt and be related to this equilibrium. Question 3: They form due to tensional forces causing faulting and block movement, often along tectonic plate boundaries or in rift zones.