Past_sea_level | TriviaQuestions.online

⭐ Core Definition: Past sea level

Global or barystatic sea level has fluctuated significantly over Earth's history. Over geologic time scales, the primary factors affecting sea level are the volume of available water due to growth or melting of ice caps, and the storage volume of the ocean basins due to plate tectonics. The secondary and tertiary influences on water volume are sedimentation, oceanic plume volcanism, the temperature of the seawater, which affects density, and the amounts of water retained in other reservoirs like aquifers, glaciers, lakes, and rivers. In addition to these global changes, local changes in sea level are caused by Earth's crust uplift, known as dynamic topography, and subsidence.

Over geologic timescales sea level has fluctuated by more than 100's of metres. In Archean times, most of the earth was covered by water, and early oceanic crust was relatively shallow. With time oceanic crustal composition changed, plate tectonics commenced at some point in the Proterozoic, and oceanic crust became older and deeper, creating oceans like we have currently. During the Phanerozoic, for which more geological information is available, i.e. marine fossils, sea level fluctuated by several 100's of meters, with the highest peaks generally reconstructed during the middle Paleozoic, and Cretaceous.

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👉 Past sea level in the context of Marine terrace

A raised beach, coastal terrace, or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin, mostly an old abrasion platform which has been lifted out of the sphere of wave activity (sometimes called "tread"). Thus, it lies above or under the current sea level, depending on the time of its formation. It is bounded by a steeper ascending slope on the landward side and a steeper descending slope on the seaward side (sometimes called "riser"). Due to its generally flat shape, it is often used for anthropogenic structures such as settlements and infrastructure.

A raised beach is an emergent coastal landform. Raised beaches and marine terraces are beaches or wave-cut platforms raised above the shoreline by a relative fall in the sea level.

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⭐ Core Definition: Past sea level
👉 Past sea level in the context of Marine terrace
Past sea level in the context of Early Holocene sea level rise

Past sea level in the context of Early Holocene sea level rise

The early Holocene sea level rise (EHSLR) was a significant jump in sea levelby about 60 m (197 ft) during the early Holocene, between about 12,000 and 7,000 years ago, spanning the Eurasian Mesolithic. The rapid rise in sea level and associated climate change, notably the 8.2 ka cooling event (8,200 years ago),and the loss of coastal land favoured by early farmers, may have contributed to the spread of the Neolithic Revolution to Europe in its Neolithic period.

During deglaciation since the Last Glacial Maximum, between about 20,000 to 7,000 years ago (20–7 ka), the sea level rose by a total of about 100 m (328 ft), at times at extremely high rates, due to the rapid melting of the British-Irish Sea, Fennoscandian, Laurentide, Barents-Kara, Patagonian, Innuitian and parts of the Antarctic ice sheets. At the onset of deglaciation about 19,000 years ago, a brief, at most 500-year long, glacio-eustatic event may have contributed as much as 10 m (33 ft) to sea level with an average rate of about 20 mm (0.8 in)/yr. During the rest of the early Holocene, the rate of sea level rise varied from a low of about 6.0–9.9 mm (0.2–0.4 in)/yr to as high as 30–60 mm (1.2–2.4 in)/yr during brief periods of accelerated sea level rise.

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Past sea level in the context of "Marine terrace"

⭐ In the context of marine terraces, past sea level is considered a primary factor in…

⭐ Core Definition: Past sea level

👉 Past sea level in the context of Marine terrace

Past sea level in the context of Early Holocene sea level rise