Final answer:
A tectonic estuary is the type of estuary formed by geological processes like faulting or folding, resulting in a sunken area that is then flooded by the sea.
Step-by-step explanation:
An estuary is a dynamic environment where fresh and salt water mix, resulting in a biome with unique ecological significance. The type of estuary formed by geological processes like faulting or folding, which leads to the creation of a sunken area that becomes flooded by the sea, is known as a tectonic estuary. This process often occurs along tectonic plate boundaries where the Earth's crust is subject to significant geologic activity.
The formation of tectonic estuaries is a result of movements within the Earth's crust, leading to the subsidence of land, which then allows sea water to flood and create these estuaries. Examples include the San Francisco Bay, which is renowned for its biodiversity and productivity among the global community of estuaries. Tectonic forces shaping these estuaries also contribute to their significant sedimentary characteristics, which can include patterns of layering and fossil abundance that are key in facies analysis in the discipline of stratigraphy.