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The Bouma sequence (after Arnold H. Bouma, 1932–2011) describes a classic set of sedimentary structures in turbidite beds deposited by turbidity currents at the bottoms of lakes, oceans and rivers. Description The Bouma sequence specifically describes the ideal vertical succession of structures deposited by low-density (i.e., low sand concentration, fine-grained) turbidity currents. An alternate classification scheme that is generally called the Lowe sequence exists for the ideal vertical sequence of structures deposited by high-density flows.The Bouma sequence is divided into 5 distinct layers labelled A through E, with A being at the bottom and E being at the top. Each layer described by Bouma has a specific set of sedimentary structures and a specific lithology (see below), with the layers overall getting finer-grained from bottom to top. Most turbidites found in nature have incomplete sequences - Bouma describes the ideal sequence where all layers are present.The layers are as follows. E: Massive, ungraded mudstone, sometimes with evidence of trace fossils (i.e., bioturbation). The Bouma E layer...

Batman: Three Jokers is an American comic book limited series published by DC Comics. It is a spiritual successor to Batman: The Killing Joke and Batman: A Death in the Family. The three-issue storyline was written by Geoff Johns and illustrated by Jason Fabok and Brad Anderson, began in August and concluded in October 2020. In Three Jokers, Batman, Batgirl and Red Hood follow a lead on the Joker, who appears to have been three different men all along. The Three Jokers storyline was published under DC Black Label, an imprint allowing writers to present unique takes on DC characters for a mature audience. The storyline received positive reviews with praise for the art, story and character development despite criticism on the underdevelopment on Red Hood and Batgirl's story. Premise Three Jokers follows Batman as he investigates several ongoing crimes by the Joker occurring simultaneously, which may be related to the possibility that there may indeed be more than one Joker operating in Gotham City.The three Jokers in this story are referred to by simple titles: ...

Ringwoodite is a high-pressure phase of Mg2SiO4 (magnesium silicate) formed at high temperatures and pressures of the Earth's mantle between 525 and 660 km (326 and 410 mi) depth. It may also contain iron and hydrogen. It is polymorphous with the olivine phase forsterite (a magnesium iron silicate). Ringwoodite is notable for being able to contain hydroxide ions (oxygen and hydrogen atoms bound together) within its structure. In this case two hydroxide ions usually take the place of a magnesium ion and two oxide ions.Combined with evidence of its occurrence deep in the Earth's mantle, this suggests that there is from one to three times the world ocean's equivalent of water in the mantle transition zone from 410 to 660 km deep.This mineral was first identified in the Tenham meteorite in 1969, and is inferred to be present in large quantities in the Earth's mantle. Olivine, wadsleyite, and ringwoodite are polymorphs found in the upper mantle of the earth. At depths greater than about 660 kilometres (410 mi), other minerals, including some with the perovskite structure, are stable. The properties of these minerals determine many...