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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, as well as by water induced erosion, such as waves. The geological composition of rock and soil dictates the type of shore that is created. Earth contains roughly 620,000 km (390,000 mi) of coastline.
Granite is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers.
The Snowball Earth is a geohistorical hypothesis that proposes during one or more of Earth's icehouse climates, the planet's surface became nearly entirely frozen with no liquid oceanic or surface water exposed to the atmosphere. The most academically mentioned period of such a global ice age is believed to have occurred some time before 650 mya during the Cryogenian period, which included at least two large glacial periods, the Sturtian and Marinoan glaciations.
The Archean Eon, in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history, preceded by the Hadean Eon and followed by the Proterozoic. The Archean represents the time period from 4,031 to 2,500 Mya. The Late Heavy Bombardment is hypothesized to overlap with the beginning of the Archean. The Huronian glaciation occurred at the end of the eon.
Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence creates a regional depression that provides accommodation space for accumulation of sediments. Over millions or tens or hundreds of millions of years the deposition of sediment, primarily gravity-driven transportation of water-borne eroded material, acts to fill the depression. As the sediments are buried, they are subject to increasing pressure and begin the processes of compaction and lithification that transform them into sedimentary rock.
Eclogite is a metamorphic rock containing garnet (almandine-pyrope) hosted in a matrix of sodium-rich pyroxene (omphacite). Accessory minerals include kyanite, rutile, quartz, lawsonite, coesite, amphibole, phengite, paragonite, zoisite, dolomite, corundum and, rarely, diamond. The chemistry of primary and accessory minerals is used to classify three types of eclogite. The broad range of eclogitic compositions has led to a longstanding debate on the origin of eclogite xenoliths as subducted, altered oceanic crust.
Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolostone), which is composed of dolomite (CaMg(CO3)2). They are usually classified on the basis of texture and grain size. Importantly, carbonate rocks can exist as metamorphic and igneous rocks, too. When recrystallized carbonate rocks are metamorphosed, marble is created. Rare igneous carbonate rocks even exist as intrusive carbonatites and, even rarer, there exists volcanic carbonate lava.
Marine pollution occurs when substances used or spread by humans, such as industrial, agricultural and residential waste, particles, noise, excess carbon dioxide or invasive organisms enter the ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. It is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide. Since most inputs come from land, either via the rivers, sewage or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor by carrying off iron, carbonic acid, nitrogen, silicon, sulfur, pesticides or dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff, wind-blown debris, and dust. These nonpoint sources are largely due to runoff that enters the ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution, bilge pollution, atmospheric pollution and, potentially, deep sea mining.
The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. Each rock type is altered when it is forced out of its equilibrium conditions. For example, an igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and change as they encounter new environments. The rock cycle explains how the three rock types are related to each other, and how processes change from one type to another over time. This cyclical aspect makes rock change a geologic cycle and, on planets containing life, a biogeochemical cycle.
Marine plastic pollution is a type of marine pollution by plastics, ranging in size from large original material such as bottles and bags, down to microplastics formed from the fragmentation of plastic material. Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. Eighty percent of marine debris is plastic. Microplastics and nanoplastics result from the breakdown or photodegradation of plastic waste in surface waters, rivers or oceans. Recently, scientists have uncovered nanoplastics in heavy snow, more specifically about 3,000 tons that cover Switzerland yearly.
Partial melting is the phenomenon that occurs when a rock is subjected to temperatures high enough to cause certain minerals to melt, but not all of them. Partial melting is an important part of the formation of all igneous rocks and some metamorphic rocks, as evidenced by a multitude of geochemical, geophysical and petrological studies.
Plastiglomerate is a rock made of a mixture of sedimentary grains, and other natural debris that is held together by plastic. It has been considered a potential marker of the Anthropocene, an informal epoch of the Quaternary proposed by some social scientists, environmentalists, and geologists.
The Qinling orogenic belt is a tectonic feature that evolved throughout the Proterozoic and Phanerozoic eons due to a variety of tectonic activities. It is a part of the Central China Orogenic Belt, aligned in an east–west orientation across Central China, and spans portions of Shaanxi, Henan and Gansu provinces along the Qinling Mountains which are one of the greatest mountain ranges in China. The first materials involved in the Qinling orogenic belt formed around 2.5 billion years ago, whereas the main morphology of the belt now largely reflects the Triassic collision between the North China Plate and the South China Plate and Cenozoic extension across China. During these 2.5 billion years, various types of rocks have been formed here due to different tectonic processes and chemical reactions between rocks. Therefore, geologists are able to reconstruct the evolution of mountain belt based on evidence preserved in these rocks.
The geology of Brazil includes very ancient craton basement rock from the Precambrian overlain by sedimentary rocks and intruded by igneous activity, as well as impacted by the rifting of the Atlantic Ocean.
Beach cleaning or clean-up is the process of removing solid litter, dense chemicals, and organic debris deposited on a beach or coastline by the tide, local visitors, or tourists. Humans pollute beaches with materials such as plastic bottles and bags, plastic straws, fishing gear, cigarette filters, six-pack rings, surgical masks and many other items that often lead to environmental degradation. Every year hundreds of thousands of volunteers comb beaches and coastlines around the world to clean this debris. These materials are also called "marine debris" or "marine pollution" and their quantity has been increasing due to anthropocentric activities.
The South China Craton or South China Block is one of the Precambrian continental blocks in China. It is traditionally divided into the Yangtze Block in the NW and the Cathaysia Block in the SE. The Jiangshan–Shaoxing Fault represents the suture boundary between the two sub-blocks. Recent study suggests that the South China Block possibly has one more sub-block which is named the Tolo Terrane. The oldest rocks in the South China Block occur within the Kongling Complex, which yields zircon U–Pb ages of 3.3–2.9 Ga.
The Western Block of the North China Craton is an ancient micro-continental block mainly composed of Neoarchean and Paleoproterozoic rock basement, with some parts overlain by Cambrian to Cenozoic volcanic and sedimentary rocks. It is one of two sub-blocks within the North China Craton, located in east-central China. The boundaries of the Western Block are slightly different among distinct models, but the shapes and areas are similar. There is a broad consensus that the Western Block covers a large part of the east-central China.
Plasticrusts are a new type of plastic pollution in the form of plastic debris, covering rocks in intertidal shorelines which vary in thickness and in color and are composed of polyethylene based on fourier-transform infrared spectroscopy (FTIR) analysis. They were first discovered on the South coast of the volcanic island of Madeira in the Atlantic Ocean in 2016 and have additionally been found on Giglio Island, Italy. They are considered a sub-type of plastiglomerate and could possibly have negative effects on surrounding fauna by entering the food web through consumption by benthic invertebrates.
The geology of New Caledonia includes all major rock types, which here range in age from ~290 million years old (Ma) to recent. Their formation is driven by alternate plate collisions and rifting. The mantle-derived Eocene Peridotite Nappe is the most significant and widespread unit. The igneous unit consists of ore-rich ultramafic rocks thrust onto the main island. Mining of valuable metals from this unit has been an economical pillar of New Caledonia for more than a century.
The Vitória-Trindade Ridge is a 1200 km long ridge in the western part of the South Atlantic at around 20 degrees south latitude and which is composed of a series of seamounts and islands. It extends from 40 degrees west on the Brazil coast to 29 degrees west. It is composed of magmatic rocks and is scientifically considered to be the volcanic track of a mantle plume impinging on the South American tectonic plate which has thrown up a series of volcanic cones over the last 140 million years since the start of the Cretaceous period. The rocks are formed of an alkaline basalt.
References
- ↑ Reporter, Jess Thomson Science (2023-12-17). "Bizarre plastic rocks now found across five continents". Newsweek. Retrieved 2024-01-04.
- ↑ Santos, Fernanda Avelar; Diório, Giovana Rebelo; Guedes, Carlos Conforti Ferreira; Fernandino, Gerson; Giannini, Paulo C. F.; Angulo, Rodolfo José; de Souza, Maria Cristina; César-Oliveira, Maria Aparecida Ferreira; dos Santos Oliveira, Angelo Roberto (2022-09-01). "Plastic debris forms: Rock analogues emerging from marine pollution". Marine Pollution Bulletin. 182: 114031. Bibcode:2022MarPB.18214031S. doi:10.1016/j.marpolbul.2022.114031. ISSN 0025-326X. PMID 35969903. S2CID 251542186.
- ↑ "A Strange Plastic Rock Has Ominously Invaded 5 Continents". Popular Mechanics. 2024-01-02. Retrieved 2024-01-04.
- ↑ Dua, Shubhangi (2023-12-19). "Study: Unconventional sedimentary rocks spotted across five continents". interestingengineering.com. Retrieved 2024-01-12.
- ↑ Snider, Mike. "'Terrifying' plastic rock finding: Pollution is embedded in this Brazilian island's geology". USA TODAY. Retrieved 2024-01-12.
- ↑ Gewin, Virginia (2023-07-31). "Plastic rocks are threatening wildlife on Brazil's easternmost island — I'm studying how". Nature. 620 (7972): 238. Bibcode:2023Natur.620..238G. doi:10.1038/d41586-023-02448-1. PMID 37524921. S2CID 260321672.
- ↑ Andrei, Mihai (2023-12-21). "Geologists say plastic rocks are now a thing". ZME Science. Retrieved 2024-01-04.
