GLY 1102 Topic 3

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___ is a detrital sedimentary rock formed by cementation of individual grains ranging in size from 1/16 to 3
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Sandstone
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Fossils are usually preserved in what kind of rocks
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sedimentary
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Unconsolidated sediments (ec, mud) are turned into sedimentary rocks (eg, shale) by a process called
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lithification
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Conglomerates and breccias are distinguished from each other on the basis of ___ their course fragments are
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how rounded or angular
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___ differs from limestone in that some of the calcium has been replaced by magnesium changing it to magnesium carbonate CaMg(CO3)2
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Dolomite
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___ is an important process in lithification causing a reduction in the pore space between unconsolidated grains in the sediment
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compaction
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Shale differs from mudstone by breaking into small pieces along bedding planes. This breakage charactristic is called ___
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fissility
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___ is the most common chemical sedimentary rock
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Limestone
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The two principal types of sedimentary rocks are called __ and __
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Detrital and chemical
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Which of the following is a common cementing material in sedimentary rocks
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All of these (silica, calcite, iron oxide)
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The White Cliffs of Dover are composed of this type of sedimentary rock made up of the calcium carbonate skeletal remains of microscopic marine algae
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Chalk
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The most commonly used grain size scale in use is the ___ Scale that divided particle size (ex: clay, silt, sand, gravel) by a specific size range in millimeters (clay is less than 1/256mm)
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Wentworth
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Sorting refers to the range of ___ in a clastic sediment or sedimentary rock
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particle size separation
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Some sedimentary rocks begin as the weathered products of existing rocks
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True
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The process of binding sediment grains together is ___ where minerals are precipitated in the pore spaces
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cementation
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A ___ limestone is composed to a large extent by the skeletal remains of invertebrate fossils (corals, sponges, bryozoans, pekecypods, echinoids)
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bioclastic
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Lithostatic pressure is the pressure resulting from the weight of the overlying rocks
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True
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Claystones do not exhibit fissility but break into blocky masses
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True
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Most chemical sedimentary rocks form from percipitation from solution in fresh water (lakes, rivers, caves, springs) or in the sea
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True
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___ are sedimentary rocks formed of minerals that were precipitated from solution with evaporation of the liquid they were dissolved in
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Evaporites
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Chert has a ___ fracture pattern, making it easy to work into tools and projectiles (arrowheads, scrapers)
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concoidal
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___ is a detrital sedimentary rock formed by cementation of individual grains ranging in size from 1/16 to 2
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Sandstone
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Sedimentary rocks have 2 types of texture: clastic (or detrital) and non-clastic (crystalline)
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True
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___ sedimentary rocks form from the organic and inorganic precipitation of minerals from an aqueous solution or the accumulation of organic matter
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Chemical
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Peat is brownish, soft, spongy and is composed almost entirely of recognizable plant remains. Burial of peat decreases its water content and gradually changes it to coal
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true
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The ___ of a particle is the degree to which the shape of the particle approaches the form of a sphere
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sphericity
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The degree of sorting reflects: the degree of mechanical and chemical weathering producing the sediment, the transportation process, and post despositional process that may alter the sediment grain size distribution
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True
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What percent of sediments are converted to sedimentary rocks and account for the exposed rocks on the Earths surface
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75
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A ___ is a coarse grained limestone composed of poorly cemented shells and shell fragments (often of nearshore species)
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Conquina
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This process is important in lithification causing a reduction in pore space between unconsolidated grains in the sediment
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compaction
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___ sedimentary rocks are formed from the accumulation of minerals and rock fragments eroded from preexisting rocks (metamorphic, sedimentary, igneous) or their weathered by products
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Detrital or Terrigenous
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Which of the following is a poorly sorted detrital sedimentary rock
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Conglomerate
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___ is a biochemical sedimentary rock composed f combustible material derived from the partial decomposition of plants
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Coal
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___ is a detrital sedimentary rock composed of grains between 1/16 and 1/256
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Siltstone
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___ is a soft chemical sedimentary rock composed almost entirely of the calcium carbonate skeletons of microscopic marine phytoplankton (coccolithophores)
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Chalk
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A conglomerate is composed predominantly of rounded to subrounded clasts, a significant proportion being gravel size
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True

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