GEOS - 5. Sedimentary Rocks
Card Set Information
GEOS - 5. Sedimentary Rocks
For Exam 1
Sedimentary rocks make up less than ___ percent of the crust.
Sedimentary rocks cover ___ percent of the continents.
Where are sedimentary rocks made?
On the surface of the earth
How is a sedimentary rock formed?
Sediment buried & squeezed
Breaking apart rock, mechanically and chemically.
The moving rock parts somewhere else
List mechanical erosion methods
Water, wind, gravity (landslides), ice
A chunk of rock; clay, sand, gravel
Define chemical erosion.
occurs when water transports dissolved minerals away from their source rocks (example: acidic rainwater dissolves limestone & it ends up in caves)
Define mechanical deposition
Slide stops, wind/water slows, ice melts
What is compaction?
Sediment compacted into a denser state,reduction in void space btn particles
Chemical precipitation in pores; filling of void spaces by chemical precipitation
What is porosity?
Measure of relative amount of void space
Besides compaction and cementation, what can also contribute to the lithification of rock?
Crystallization; crystal growth w/in the void spaces in a rock
Define clastic sedimentary rock.
Sediments --> rock
What are the types of sediments ordered from small to large?
Clay, sand, gravel
What is the most common mineral in sand?
What depositional environments will you get poorly sorted clastic sediments?
landslade, glacier, slow streams
What depositional environments will you get well sorted clastic sediment?
Slow streams & wind, beach (waves)
What sediment makes conglomerate?
rounded gravel particles, sediments of high-velocity streams
Like conglomerate except w/ angular particles
Made of sand, quartz
10% of sedimentary rocks
strong, hard to eroid
Made of clay
2/3 of all sedimentary rocks are shale
splits into thin slabs (fissile)
weak, easy to erode
What is oomicrite?
rock containing abundant oolites w/in a muddy matrix
How is a chemical sedimentary rock created?
Chemical transport of rock particles - dissolved in water, deposit chemically
How is limestone formed?
Biochemical, from shells on seafloor (calcite), dissolved over 100s-10,000 of years
strong, easy to erode because it is water soluble
changes through time rapidly on a geological scale
What percentage of sedimentary rocks is limestone?
What are other important chemical sedimentary rocks?
How is iron ore formed?
Water with dissolved iron but cannot be oxidated
Name two evaporites.
Describe the strength of an evaporite.
Extremely weak, behaves as plastic material under pressure.
What is bedding?
Sediment laid down in layers/beds/strata
What is stratigraphy?
Study of layers and what has happened at a particular time; the branch of geology that deals w/ the horizontal and vertical changes and relationships between sedimentary rock units
What is uniformitarianism?
The processes used to understand rocks and rocks used to understand processes
What is a fossil?
Remains of life (footprints, burrows, feces, etc.)
What are facies?
Depositional environments that are divided into subenvironments
What sedimentary rocks are most likely to form on a steep slope?
Clastic, bad sorting, many types of rock, conglomerate
What sedimentary rocks are most likely to form on a glacier?
Clastic, bad sorting, contains large particles, conglomerate
What sedimentary rocks are most likely to be formed at a desert by wind?
clastic, well-sorted, sand --> sandstone
What sedimentary rocks are most likely to be formed at a desert by evaporatoin?
Chemical-evaporation of water, salt, phosphates, & gypsum
What sedimentary rocks are most likely to be formed by wind-blow dusty soils?
caused by drought and bad agricultural practices, clastic, very good sorting, shale
What sedimentary rocks are most likely to be formed in a fast-moving river?
bad sort, boulders & gravel.
What sedimentary rocks are most likely to be formed in a slow-moving river?
Clay & sand, good sorting
What sedimentary rocks are most likely to be formed at the mouth of a river?
sand & clay, really good sorting
What is a delta?
When the river hits the sea
What sedimentary rocks are most likely to be formed at a lake?
really fine-grained sediments deposited on lake bed, good sorting
What sedimentary rocks are most likely to be formed in a swamp?
sediment made out of plants --> coal (dead stuff that never gets biodegraded)
What sedimentary rocks are most likely to be formed on a coast?
Waves --> very well sorted; sand & pebbles from river mouths or weather/erosion
What sedimentary rocks are most likely to be formed at a coral reef?
What sedimentary rocks are most likely to be formed in the deep ocean?
mix of stuff to make chert, oil, and limestone
What are Appalachian Valley & Ridge ridges made of?
shale, sandstone, limestone; ridge top: sandstone
What are Appalachian Valley & Ridge valleys made of?
shales and limestone
What sedimentary rocks are mined for construction?
gravel, sand, brick, cement, limestone, sandstone
What chemicals serve as resources?
lime, salts, fertilizer, gypsum (plaster), iron ore
lime is an important ___.
What percent of energy comes from fossil fuels?
Most groundwater usage is from ___.
Sediment & sedimentary rock
What is the porosity and permeability of shale?
low porosity, low permeability.
What is the porosity and permeability of sandstone?
high porosity, high permeability
What is the porosity and permeability of limestone?
irregular porosity, highly irregular limestone; water flows fast through caves and cracks.
Is clay fertile?
Is clay permeable?
Is sand fertile?
Is sand permeable?
What does detrital origin mean?
when fragments have been eroded, transported, and deposited.
What does nonclastic mean?
grains form an interlocking network similar to igneous rocks w/ crystalline texture.
What is parallel bedding produced by?
Transport of sediment by currents or by deposition in standing bodies of water where sediment particles fall through a column of water to their resting points on the bottom.
What is cross bedding?
Result of deposition of sediment that moved in wavelike bedforms near sediment-fluid interface