We can understand from the passage that the destructive forces of erosion and the constructive power of tectonics —.

Mountains have always evoked awe and inspired artists and adventurers throughout human existence. More recent research has ted to important new insights into how mountains, the most magnificent of the Earth's formations, came to be the way they are. Mountains are created and shaped, it now appears, not only by the movements of the vast tectonic plates that make up the Earth's exterior but also by factors such as climate and erosion. In particular, the interactions between tectonic, climatic and erosional processes exert strong control over the shape and maximum height of the mountains as well as the amount of time necessary to build - or destroy - a mountain range. Paradoxically, the shaping of mountains seems to depend as much on the destructive forces of erosion as on the constructive power of tectonics.