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An example of a minor avulsion is known as a meander cutoff, when a pronounced meander (hook) in a river is breached by a flow that connects the two closest parts of the hook to form a new channel. This occurs when the ratio between the channel slope and the potential slope after an avulsion is less than about 1/5. [1]
The opposite of transgression is regression where the sea level falls relative to the land and exposes the former sea bottom. During the Pleistocene Ice Age, so much water was removed from the oceans and stored on land as year-round glaciers that the ocean regressed 120 m, exposing the Bering land bridge between Alaska and Asia.
During the Permian-Triassic extinction, the largest extinction event in the Earth's history, the global sea level fell 250 m (820 ft). [ 3 ] A major regression could cause marine organisms in shallow seas to go extinct, but mass extinctions tend to involve both terrestrial and aquatic species, and it is harder to see how a marine regression ...
The Atlantic Ocean is teeming with life, but for the first time researchers have discovered dead zones in these waters - areas low in both oxygen and salinity - off the coast of Africa. Fish can't ...
Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This causes the oceanic plate to buckle and usually results in a new mid-ocean ridge forming and turning the obduction into subduction.
Some fracture zones such as Chile and Valdivia make up large sections of the Nazca-Antarctic plate boundary. Map of the Chile Rise and its fracture zones in Nazca and the Antarctic plates Active Pacific Ocean fracture zones are perpendicular to the mid-ocean ridges (black lines) in orange shaded region. Since the map was prepared ages not shown ...
Increased ocean stratification reduces the introduction of nutrients from the deep ocean into the euphotic zone resulting in decreases in both net primary production and sinking particulate matter. [3] Additional research suggests shifts in the geographical range of many species could also occur with warming, with many of them shifting poleward ...
Fracture zones represent the previously active transform-fault lines, which have since passed the active transform zone and are being pushed toward the continents. These elevated ridges on the ocean floor can be traced for hundreds of miles and in some cases even from one continent across an ocean to the other continent.