Valleys and mountain ranges are typically formed by tectonic activity, specifically through processes like plate tectonics and faulting. When two tectonic plates collide, one may be pushed up and over the other, forming a mountain range. As the crust is compressed, rocks are folded and faulted, causing layers of earth to rise upwards. Valleys, on the other hand, can form through processes like erosion or the spreading apart of plates, which creates a depression in the landscape. Rivers and glaciers can also play a significant role in carving out valleys over time.
