What is the geological term for a round depression of rock layers?

The term for a round depression of rock layers is a basin. Basins are geological features that form when sedimentary rocks accumulate over time in a low area. This may occur due to processes such as subsidence, where the Earth's crust sinks due to tectonic activity or erosion that removes overlying materials. The key characteristic of a basin is its concave shape, which is designed to trap and hold sediments, making them essential for understanding sedimentary processes and the historical geology of an area.

Domes, although they can also have a similar geological structure, are typically characterized by an upward bulging of rock layers, which creates a convex shape rather than a depression. Synclines refer to downfolds in rock layers that create trough-like structures, but they are not exclusively round and usually appear in elongated configurations. Faults represent fractures in the Earth's crust where blocks of rock have moved past each other, which does not pertain to depressions. Hence, the distinction among these geological terms helps in identifying features based on their shapes and formation processes.