Science Olympiad Dynamic Planet Practice Test 2025 - Free Practice Questions and Study Guide

An intermountain basin is defined as a valley that is situated between mountain ranges. This geological formation occurs when surrounding mountain ranges create a depression or a low-lying area, allowing for the accumulation of sediment, vegetation, and water, which can lead to the formation of lakes or rivers within the basin.

These basins are typically characterized by their relatively closed geography, which can influence both their climate and ecology. The presence of mountains on either side can lead to unique weather patterns, often resulting in varying precipitation levels compared to the surrounding areas.

Understanding this definition helps to clarify the significance of intermountain basins in terms of their geological and ecological roles within mountainous regions. Other options reference different geological features that do not specifically describe the characteristics of an intermountain basin, such as ocean sedimentation, backarc basins related to tectonic activity, or exclusively volcanic activity involving lava. Thus, the correct identification of the intermountain basin as a valley between mountain ranges is essential for grasping the concepts of earth science and geology.