Regional metamorphism produces nonfoliated metamorphic rocks in the depths of mountain ranges, which erosion eventually exposes as "mountain roots" hundreds of kilometers wide and thousands of kilometers long. True / False.

False.

Explanation:

Regional metamorphism is a common type of metamorphism involving the effects and cooperation of directed pressures and shearing stress as well as a wide range of confining pressures and temperatures. The heat element facilitates recrystallisation; but the stress element not only promotes recrystallisation, but is powerful in deforming the rocks, and producing new structures.

It is related both geographically and genetically to large orogenic belts, and hence is regional in character.

Regional metamorphism does NOT produce nonfoliated metamorphic rocks in the depths of mountain ranges. Regional metamorphism takes place at deeper regions of the crust and is, as the name already signifies, of regional extent. The different types of regional metamorphism, or still dynamothermal metamorphism, are confined to areas of mountain building, so that metamorphism as well as orogenesis ought to be regarded as due to one and the same process.