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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.
At the height of the last ice age, around 18,000 years ago, the global sea level was 120 to 130 m (390-425 ft) lower than today. A cold spell around 6 million years ago was linked to an advance in glaciation, a marine regression, and the start of the Messinian salinity crisis in the Mediterranean basin.
An estuarine salt marsh along the Ōpāwaho / Heathcote River, Christchurch, New Zealand Salt marsh on Sapelo Island, Georgia, US. Salt marshes occur on low-energy shorelines in temperate and high-latitudes [5] which can be stable, emerging, or submerging depending if the sedimentation is greater, equal to, or lower than relative sea level rise (subsidence rate plus sea level change ...
A graph shows the groundwater level and sea level changes with respect to the tide on a small island in Portugal. The solid line represents the sea level change in the estuary and the dotted line is date from a piezometer that installed 50 m apart from the coastal line. It shows a time lag between the sea tide and the tide of groundwater.
Salt marshes can be generally divided into the high marsh, low marsh, and the upland border. The low marsh is closer to the ocean, with it being flooded at nearly every tide except low tide. [ 53 ] The high marsh is located between the low marsh and the upland border and it usually only flooded when higher than usual tides are present. [ 53 ]
In sharp contrast, the period between 14,300 and 11,100 years ago, which includes the Younger Dryas interval, was an interval of reduced sea level rise at about 6.0–9.9 mm/yr. Meltwater pulse 1C was centered at 8,000 years ago and produced a rise of 6.5 m in less than 140 years, such that sea levels 5000 years ago were around 3m lower than ...
The sea-level equation (SLE) is a linear integral equation that describes the sea-level variations associated with the PGR. The basic idea of the SLE dates back to 1888, when Woodward published his pioneering work on the form and position of mean sea level , [ 45 ] and only later has been refined by Platzman [ 46 ] and Farrell [ 47 ] in the ...
Sea level rise of 0.2-0.3 meters is likely by 2050. In these conditions what is currently a 100-year flood would occur every year in the New Zealand cities of Wellington and Christchurch. With 0.5 m sea level rise, a current 100-year flood in Australia would occur several times a year.