Pelagic red clay
Pelagic red clay, also known as simply red clay, brown clay or pelagic clay, is a type of pelagic sediment.
Pelagic clay accumulates in the deepest and most remote areas of the ocean. It covers 38% of the ocean floor and accumulates more slowly than any other sediment type, at only 0.1–0.5 cm/1000 yr. Containing less than 30% biogenic material, it consists of sediment that remains after the dissolution of both calcareous and siliceous biogenic particles while they settled through the water column. These sediments consist of eolian quartz, clay minerals, volcanic ash, subordinate residue of siliceous microfossils, and authigenic minerals such as zeolites, limonite and manganese oxides. The bulk of red clay consists of eolian dust. Accessory constituents found in red clay include meteorite dust, fish bones and teeth, whale ear bones, and manganese micro-nodules.
These pelagic sediments are typically bright red to chocolate brown in color. The color results from coatings of iron oxide and manganese oxide on the sediment particles. In the absence of organic carbon, iron and manganese remain in their oxidized states and these clays remain brown after burial. When more deeply buried, brown clay may change into red clay due to the conversion of iron hydroxides to hematite.
Pelagic zone
Any water in a sea or lake that is neither close to the bottom nor near the shore can be said to be in the pelagic zone. The word "pelagic" is derived from Greek πέλαγος (pélagos), meaning "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes from the surface of the sea almost to the bottom. Conditions differ deeper in the water column such that as pressure increases with depth, the temperature drops and less light penetrates. Depending on the depth, the water column, rather like the Earth's atmosphere, may be divided into different layers.
The pelagic zone occupies 1,330 million km3 (320 million mi3) with a mean depth of 3.68 km (2.29 mi) and maximum depth of 11 km (6.8 mi). Fish that live in the pelagic zone are called pelagic fish. Pelagic life decreases with increasing depth. It is affected by light intensity, pressure, temperature, salinity, the supply of dissolved oxygen and nutrients, and the submarine topography, which is called bathymetry. In deep water, the pelagic zone is sometimes called the open-ocean zone and can be contrasted with water that is near the coast or on the continental shelf. In other contexts, coastal water not near the bottom is still said to be in the pelagic zone.
Clay
Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Clays are plastic due to their water content and become hard, brittle and non–plastic upon drying or firing. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Depending on the content of the soil, clay can appear in various colours, from white to dull gray or brown to a deep orange-red.
Clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in particle size and other physical properties, and many naturally occurring deposits include both silts and clay. The distinction between silt and clay varies by discipline. Geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm (clays being finer than silts), sedimentologists often use 4–5 μm, and colloid chemists use 1 μm.Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger.
Mythimna ferrago
Mythimna ferrago, the clay, is a moth of the family Noctuidae. It is distributed throughout Europe and is also found in Morocco, Algeria, Turkey, Asia Minor, Armenia, Syria, Turkestan, Israel, Lebanon, Iraq, Iran, Central Asia and the western parts of temperate North Asia. Also Tibet.
The forewings of this species vary from buffish to orangey brown, usually with a darker central line running longways down the wing, interrupted by a pale stigma. There are usually a few small dark spots in the basal area. The hindwings are dark grey with paler margins. The male is easily recognizable by a triangular area of black hair on the underside of the abdomen. The wingspan is 36–44 mm. This moth flies at night in July and August and is attracted to light and sugar.
Technical Description and variation
The wingspan is 36–44 mm. Forewing pale greyish rufous, speckled with dark;lines indistinct, dark grey; the outer regularly lunulate-dentate, the teeth marked by black dashes on veins;reniform stigma obscure, ending in a cloudy pale spot at lower end of cell; hindwing greyish ochreous; ventral tufts black. The species varies in coloration: ferrago F. is the reddest form: - grisea Haw, is grey without any rufous admixture, with the markings generally clearer; fulvescens Tutt is rare, with fulvous in the place of red; — ab. marginata Tutt has silvery grey hindwings with broad dark border.
Clay (short story)
"Clay" is a short story by James Joyce published in his 1914 collection Dubliners.
The story
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