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Shale is characterized by its tendency to split into thin layers less than one centimeter in thickness. This property is called fissility. [1] Shale is the most common sedimentary rock. [2] The term shale is sometimes applied more broadly, as essentially a synonym for mudrock, rather than in the narrower sense of clay-rich fissile mudrock. [3]
The new thought is that these ocean currents were slowed by blooms of microscopic marine primary producers, which allowed for the settlement of organic-rich sediments at the seafloor, producing many of the economically productive black shale beds that are present today. To this day it remains an intensely researched subject by scholars and ...
Graptolitic argillite (also known as dictyonema argillite, dictyonema oil shale, dictyonema shale, or Tremadocian black shale) is a marinite-type black shale of sapropelic origin. It is a blackish to greyish lithified claystone.
For example, concretions in sandstones or shales are commonly formed of a carbonate mineral such as calcite; those in limestones are commonly an amorphous or microcrystalline form of silica such as chert, flint, or jasper; while those in black shale may be composed of pyrite. [18]
What do the Black History Month colors mean and what are their origins? Design by Yoora Kim. When you see posters and graphics related to Black History Month, chances are you'll see them designed ...
What Does ‘The Black Dog’ Mean? The term “black dog” was initially coined in the 1700s to describe “a brief period in a person’s life” but has since expanded to cover the spectrum of ...
Shale is lithified and cleavable. It must have at least 50-percent of its particles measure less than 0.062 mm. This term is confined to argillaceous, or clay-bearing, rock. There are many varieties of shale, including calcareous and organic-rich; however, black shale, or organic-rich shale, deserves further evaluation.
Its first printed use came as early as 1991 in William G. Hawkeswood's "One of the Children: An Ethnography of Identity and Gay Black Men," wherein one of the subjects used the word "tea" to mean ...