GLY 1102 Topic 3

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___ differs from limestone in that some of the calcium has been replaced by magnesium changing it to magnesium carbonate CaMg(CO3)2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