sedimentary HWK
other than sand dunes in a desert environment, where else would you expect to find well-rounded and sorted sand deposits?
beach
abundant plant material accumulating in a swampy environment with ____ is required for peat to form.
low oxygen levels
what are the three broad categories of sedimentary environments with an example of each?
marine environments, such as deep ocean floors; continental environments, such as deserts; transitional environments, such as tidal flats
how is anthracite produced from bituminous coal?
metamorphism
what is the raw material for coal, and how does it accumulate?
plants are the raw material for coal; to form coal plants must accumulate in oxygen deficient swamp water.
in your field area you find a quartz sandstone unit with cross-bedding in it that is on the order of 2 m high. in what environment would you deduce this rock formed?
sand dunes
describe the distribution of sedimentary deposits you would expect to find on a delta.
sand in channels, mud on floodplain
what is the sequence of sediments you would pass over if you were to walk from the shoreline and then swim in the offshore direction?
sand, clay, carbonate
why are sedimentary rocks important?
sedimentary rocks provide geologist with information necessary to study the history of the Earth and also hold various resources of economic importance.
by which process do sediments become well sorted, and by what process do sediments become poorly sorted?
sediments that are transported for a long, sustained time tend to become well sorted, whereas sediments that are transported over a rather short period of time tend to be poorly sorted.
the same formation changes laterally from layered evaporites to mudcracked sandstone to conglomerate. using the facies concept, what is an accurate interpretation?
shallow lake, shoreline, mountain front setting
in the United States, the most common type of coal is _____ and the largest producing state is ______.
sub-bituminous: Wyoming.
what is a diagenesis?
the chemical, physical, and biological changes that take place after sediments have been deposited and during and after sediment lithification.
which of the following is a reason that limestone is formed in a relatively offshore position?
the lack of sediments derived from land.
which of the following is a likely explanation for why there is limestone near the summit of Mount Everest, the tallest mountain on Earth?
the limestone found at the top of Mount Everest was formed in an ocean.
chemical sedimentary rocks form from ____.
the precipitation of ions in solution.
the three basic sedimentary rock categories are
-detrital rocks, which are composed of solid particles -chemical rocks, which are composed of ions that precipitated from solution -organic rock, which forms from the carbon-rich remains of organisms
which structure is common in sedimentary rock?
-mudcracks -ripple marks -cross-bedding -fossils
where are most sediments and sedimentary rocks found?
-on the surface of continents -on the ocean floor
name the profession of coal types with increased heat and pressure from burial.
-peat -lignite -bituminous -anthracite
what is a delta?
a delta is a triangular landform created where a stream enters a body of water and deposits sediments.
neighboring sedimentary facies generally show ________.
a gradational relationship.
for a detrital sedimentary rock that contains mud cracks, you could be confident that the environment in which it formed was _____.
alternately wet and dry
what is the definition of depositional environment?
an area where sediment was deposited under certain condition in Earth's past.
differentiate between the formation of biochemical rocks and the formation of inorganic chemical rocks.
biochemical rocks form from organisms that were once alive, such as limestone from marine shells, whereas inorganic chemical rocks form from non-biological processes, such as salt that is left behind when a lake evaporates.
what coal is soft, black in color, and produces soot upon handling?
bituminous
the geologic laboratory where you work received a sample for analysis that is composed of calcite that includes many microscopic fossils of marine organisms and react with acid. what name would identify this rock?
chalk
which two minerals are most common in detrital sedimentary rocks?
clay minerals and quartz
working in the field, you find a rock that contains rounded fragments that are greater than 2 mm in diameter. what would you call this rock?
conglomerate
how are conglomerate and breccia different?
conglomerate has rounded grains: breccia has angular grains.
which type of sedimentary structure is characteristic of sand dunes?
cross-bedding
what is the most abundant chemical sedimentary rock in Earth's crust?
limestone
in which depositional environment would breccia form?
glacial deposits
what property of detrital sedimentary rocks can be indicative of the energy of sediment transport?
grain size
during the process that forms sedimentary rocks, how does compaction affect sediments?
it decreases the volume of pore spaces.
by what process do ooids form?
layers of CaC)3 are precipitated out of seawater and coat grains.