What defines a spit in coastal geography?

A spit is specifically identified as a narrow piece of land that extends into the sea, formed by the deposition of sediment. This geological feature typically forms where there is a change in the direction of the coastline, allowing longshore drift to transport sediment and accumulate it at a certain point. As waves and currents transport materials, sand and other sediments are deposited, gradually building out from the land and creating this elongated landform.

The relationship between the processes of erosion and deposition is crucial to understanding how spits form, as they occur in coastal areas where sediment supply is ample and the conditions allow for its accumulation. Spits often connect to the mainland at one end and extend out into the body of water, creating an important interface between marine and terrestrial ecosystems.

In contrast, the other options represent different coastal features or processes that do not fit the specific definition of a spit. For example, tall cliffs and underwater trenches pertain to erosion and deeper geological formations, while a large body of water surrounded by land refers more commonly to lakes or inland seas. These distinctions clarify why a spit is distinctly defined by its sedimentary and depositional characteristics in coastal environments.