Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
33 Cards in this Set
- Front
- Back
Sedimentary rocks can form |
By the cementing together of loose grains of preexisting rock From shell fragments or carbon-rich relicts of plants From shell fragments or carbon-rich relicts of plants |
|
Choose the proper listing of detritus terms, going from smallest to largest: slit, sand, pebbles, cobbles |
Mud, silt, sand, pebbles, cobbles |
|
Identify the TRUE statement: - Conglomerates consist of a single grain size. - Pieces of broken rock produced by physical weathering are collectively called clasts or detritus. - A well-sorted clastic rock is made up of different-sized particles. - An immature clastic rock has well-sorted, resistant grains. |
Pieces of broken rock produced by physical weathering are collectively called clasts or detritus. |
|
Which of the following features indicates the top of a sedimentary bed, or bed-surface, marker? |
Scour marks, fossil footprints, graded bedding, mud cracks |
|
T/F: Lithification is a general term used to describe all the physical, chemical, and biological processes that make a sedimentary rock from sediments. |
True |
|
A nonmarine clastic sedimentary rock composed of angular fragments surrounded by matrix is |
Breccia |
|
A clastic sedimentary rock with clay and silt-sized grains that breaks in thin sheets is called |
Shale |
|
Which term has nothing to do with the mineral calcite? |
Chert (made of the mineral quartz) |
|
Which of the following is an organic sedimentary rock originated as decaying plant matter is |
Coal |
|
Identify the TRUE statement: - Both chert and limestone may have either chemical or biochemical origin. - Chemical sedimentary rocks are crystalline in texture. - Gypsum and halite are evaporite minerals. - Flint, jasper, agate, and petrified wood are all varieties of the siliceous rock chert. |
All are correct. |
|
Ripple marks on a bedding plane |
Could suggest an ancient stream bed or a seashore |
|
What is the most logical past environment to have produced a deposit consisting of layers of unsorted, unstratified sedimentary clasts, clay-sized to boulder-sized? |
Glacial valley |
|
Geologists find a thick sequence of alternating shales and sandstones. The probable depositional environment and interpretation of these are: |
Deep-marine deposits near the continental shelf. |
|
The structure that may form where a stream enters a lake |
Has sloping foreset beds of gravel and sand Has nearly horizontal silty bottomset beds on the lake floor Has nearly horizontal topset beds composed of gravel Is called a delta |
|
Which of the following geological features was NOT formed by sedimentary processes? |
Columbia river plateau |
|
Which of the following sedimentary features is the surest indicator that the past environment was deep water? |
Turbidites |
|
T/F: Sedimentary rocks differ from igneous rocks in that sedimentary rocks can never be crystalline in texture and igneous rocks always are crystalline. |
False |
|
The words weathering and erosion are synonyms; they can be used interchangeably. |
False |
|
Graywacke and conglomerate are examples of well-sorted rocks; claystone and siltstone are examples of poorly sorted rocks. |
False |
|
The formation of dolostone, due to the introduction of magnesium into limestone, is an example of diagenesis. |
True |
|
The word fluvial means lake. |
False |
|
Obvious sandstone beach deposits overlain by marine mudstone indicate transgression of the sea. |
True |
|
Diagenesis and metamorphism both alter the texture and mineral composition of rock; metamorphism is the higher temperature process. |
True |
|
A sequence of sedimentary beds, traceable across a region and distinctive enough to be recognized as a unit is called a stratigraphic formation. |
True |
|
Which of the following is NOT one of the major classes of sedimentary rocks? |
Intrusive (it's igneous) |
|
Formation of a clastic sedimentary rock involves five stages. Which of the following describes lithification? |
Compaction and cementation of loose particles to form solid rock |
|
As sediment is transported downstream, away from its point of origin, the particles found in the stream become |
Rounder, smaller, of greater resistance, better sorted by size |
|
Rocks formed dominantly from the calcium carbonate shells of marine organisms are classified as _____ and called _____. |
Biochemical and limestone |
|
Ripple marks, dunes, and cross bedding are useful indicators of |
Current direction |
|
A sedimentary basin that forms when continental lithosphere is stretched, causing down-dropped crustal blocks bordered by narrow mountain ranges and alluvial fans, is called a |
Rift basin |
|
Sediments in a passive-margin basin are primarily fluvially derived but can also include carbonates. |
True |
|
When sea level rises, the shoreline migrates inland, flooding the land and depositing coastal sediments over preexisting terrestrial sediments. This process is called |
Transgression |
|
33 |
33 |