Coastal region in the context of "Purple Earth Hypothesis"

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⭐ Core Definition: Coastal region

A coast (also called the coastline, shoreline, or seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, such as that caused by waves. The geological composition of rock and soil dictates the type of shore that is created. Earth has about 620,000 km (390,000 mi) of coastline.

Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor ecosystems, such as freshwater or estuarine wetlands, that are important for birds and other terrestrial animals. In wave-protected areas, coasts harbor salt marshes, mangroves, and seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic animals. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals (e.g. mussels, starfish, barnacles) and various kinds of seaweeds.

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Coastal region in the context of Purple Earth hypothesis

The Purple Earth hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin-based chlorophyll, making the surface biosphere appear purplish rather than its current greenish color. It is estimated to have occurred between 3.5 and 2.4 billion years ago during the Archean eon, prior to the Great Oxygenation Event and Huronian glaciation.

Retinal-containing cell membranes exhibit a single light absorption peak centered in the energy-rich green-yellow region of the visible spectrum, but transmit and reflect red and blue light, resulting in a magenta color. Chlorophyll pigments, in contrast, absorb red and blue light, but little or no green light, which results in the characteristic green reflection of plants, cyanobacteria, green algae, and other organisms with chlorophyllic organelles. The simplicity of retinal pigments in comparison to the more complex chlorophyll, their association with isoprenoid lipids in the cell membrane, as well as the discovery of archaeal membrane components in ancient sediments on the Early Earth are consistent with an early appearance of life forms with purple membranes prior to the turquoise of the Canfield ocean and later green photosynthetic organisms.

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LINKED FROM (PARENTS)
← Purple Earth hypothesis ← Purple Earth Hypothesis
LINKS TO (CHILDREN)
Sunrise → Jersey Shore → Spring Lake, New Jersey → New Jersey → West Coast, New Zealand → Greenland → Escorca → Serra de Tramuntana → Balearic Islands → Land → Sea → Ocean → Lake → Topography → Erosion → Wind wave → Geology → Rock (geology) → Soil → Earth → Ecosystem → Biodiversity → Freshwater marsh → Estuary → Wetland → Terrestrial animal → Salt marsh → Mangrove → Seagrass meadow → Nursery habitat → Fish → Shellfish → Aquatic animal → Rocky shore → Sessility (motility) → Mussel → Starfish → Barnacle → Seaweed →