What is an uplifted block bounded by normal faults called?

An uplifted block bounded by normal faults is referred to as a horst. This geological term describes a section of the Earth's crust that has been raised or uplifted relative to the surrounding area due to tectonic forces. In normal faulting, blocks of the Earth’s crust move vertically—one block slips downwards, forming a graben, while the adjacent block is pushed upwards, resulting in a horst.

Understanding this concept is essential in geology because it relates to how the Earth's crust responds to tectonic forces and how landscapes are formed through these processes. Horsts can contribute to the formation of mountain ranges and affect local ecosystems by altering drainage patterns and elevating specific regions.

In geological terms, the other options represent different structures: a block is too general and does not specifically refer to an uplifted structure; a graben is the opposite of a horst, indicating a lowered block; and basement typically refers to the older, often crystalline rock beneath sedimentary layers, rather than an uplifted feature. Thus, horst is the specific term that accurately describes the uplifted block in question.