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A blowhole is also the name of a rare geologic feature in which air is blown through a small hole at the surface due to pressure differences between a closed underground system and the surface. The blowholes of Wupatki National Monument are an example of such a phenomenon. It is estimated that the closed underground passages have a volume of at ...
A geo or gio (/ ɡ j oʊ / GYOH, from Old Norse gjá [1]) is an inlet, a gully or a narrow and deep cleft in the face of a cliff. Geos are common on the coastline of the Shetland and Orkney islands. They are created by the wave driven erosion of cliffs along faults and bedding planes in the rock. Geos may have sea caves at their heads. Such sea ...
The Pancake Rocks are a heavily eroded limestone formation where the sea bursts through several vertical blowholes during incoming swells, particularly at high tide. The limestone was formed in the Oligocene period (around 22–30 million years old), a period in the geological history of New Zealand where most of the continent of Zealandia was submerged beneath shallow seas. [2]
Littoral caves may be found in a wide variety of host rocks, ranging from sedimentary to metamorphic to igneous, but caves in the latter tend to be larger due to the greater strength of the host rock. However, there are some notable exceptions as discussed below. In order to form a sea cave, the host rock must first contain a weak zone.
Diapirs in a subducting plate boundary. A diapir (/ ˈ d aɪ. ə p ɪər /; [1] [2] [3] from French diapir, from Ancient Greek διαπειραίνω (diapeiraínō) 'to pierce through') is a type of intrusion in which a more mobile and ductilely deformable material is forced into brittle overlying rocks.
The formation of this harbour has occurred due to active erosional processes on an extinct shield volcano, whereby the sea has flooded the caldera, creating an inlet 16 km in length, with an average width of 2 km and a depth of −13 m relative to mean sea level at the 9 km point down the transect of the central axis. [5]
Mass wasting, also known as mass movement, [1] is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice.
Because the continental rise lies below the continental slope and is formed from sediment deposition, it has a very gentle slope, usually ranging from 1:50 to 1:500. [1] As the continental rise extends seaward, the layers of sediment thin, and the rise merges with the abyssal plain, typically forming a slope of around 1:1000.