Final answer:
Low areas in mountains that allow passage through them are called 'passes'. These are different from plateaus, which are larger, flat elevated areas. Tectonic plate activity and erosion are significant factors that shape these features. Option b. passes is the correct answer.
Step-by-step explanation:
Low areas in mountains are called passes. A pass, also known as a gap, notch, col, or saddle, is a navigable route through a mountain range or over a ridge. Passes are crucial for trade, travel, and the movement of armies throughout history. Unlike plateaus, which are large flat areas elevated above their surroundings, passes are relatively narrow. The names of geographical features such as Basin and Range, Blue Ridge, Cascade-Sierra Mountains, Colorado Plateaus, and the Columbia Plateau refer to different types of geological formations. A pass provides a way through these formations without having to scale to the top of the mountains.
Factors like tectonic plate activity have shaped the earth's landscape, creating various mountain ranges and plateaus. High mountain ranges can have peaks reaching over 15,000 feet, and in some cases, they can even boast permanent glaciers due to their high elevations, as seen in New Guinea's mountains. In contrast, lower-lying mountains, such as South Africa's Cape Ranges, generally do not exceed heights of 6,000 feet. Over time, weathering and erosion can wear down these mountains, making lower mountain belts potentially older than higher ones due to the gradual reduction in elevation back to base level.
An understanding of geological features and the processes that create them, such as tectonic plates convergence and the weathering of mountain ranges, is vital for interpreting the topography of the Earth. When looking at a topographic map, one can see evidence of these processes and differentiate between older and newer geological formations by changes in elevation and erosion patterns.