Quiz 6: Sediment and Sedimentary Rocks

Sedimentary rocks can form from the deposition of solid particles eroded from pre-existing rock or from the deposition of the hard parts of organisms.

Sediments are unconsolidated, which means the grains are separate and unattached to one another.

Clay is the finest sediment.

Boulders include all rounded particles coarser than 2 mm in diameter.

Lithification is the general term for the processes that convert loose sediment into a sedimentary rock.

Most sediment is transported some distance by gravity, wind, water or ice.

The environment of deposition is determined by the location in which deposition occurs.

Detrital sedimentary rocks form from cemented sedimentary grains that are fragments of a preexisting rock.

Sedimentary breccia is a sedimentary rock formed by cementation of coarse angular fragments of rubble.

A sandstone with more than 25% sand-sized feldspar is an arkose.

Plate tectonics do not influence the distribution of sedimentary rocks.

Most shale contains both clay-sized and silt-sized particles.

Limestone is a sedimentary rock composed mostly of the mineral calcite.

Chalk is not a sedimentary rock.

Sorting is the process by which sediment grains are selected and separated according to grain size.

Dolostone (dolomite) often forms from limestone.

All evaporites have a crystalline texture.

Sedimentary structures are features found in sedimentary rocks that provide clues that help interpret their transport and deposition.

The principle of superposition states that in a stack of horizontal layers the oldest layer is on top.

Mud cracks form only in sediment exposed above water.

In order of decreasing size (largest listed first), sedimentary grain sizes include __. A) clay, sand, silt, and gravel B) gravel, sand, clay, and silt C) sand, gravel, silt, and clay D) gravel, sand, silt, and clay E) gravel, silt, sand, and clay

_____ is a coarse-grained sedimentary rock formed by the cementation of rounded gravel. A) Breccia B) Mega sandstone C) Pebble rock D) Boulder rock E) Conglomerate

Silt is mostly composed of ___ grains. A) clay mineral B) feldspar C) quartz D) mica E) calcite

Sand grains can be distinguished from silt grain by ____. A) the gritty feel between the teeth B) seeing the individual sand grains C) composition of the grains D) the gritty feel between the fingers. E) only by a microscope

Under what conditions is a sediment considered to be well-sorted? A) when the grains contains a wide variety of grain sizes mixed together B) when the grains contains just one general grain size and one mineral C) when the grains are in individual layers D) when the grains are nearly all the same size E) when the grains contain just one or two general grain sizes

____ is the process by which sediment grains are selected and separated according to grain size by agent of transportation. A) Sorting B) Grading C) Distillating D) Selection E) Segregation

_____ is a term that describes a series of visible layers in sedimentary rock. A) Units B) Tables C) Sheets D) Planes E) Bedding

______ is the shift to a tighter packing of sediment grains due to the weight of overburden. A) Cementation B) Recrystallization C) Preservation D) Compaction E) Deposition

______ is the general term for the processes that convert loose sediment into sedimentary rock. A) Gluing B) Hardening C) Crystallization D) Lithification E) Stiffening

The most common cements are _____ and ____. A) hematite; limonite B) dolomite; halite C) calcite; quartz D) olivine; pyroxene E) feldspar; mica

The most common type of sedimentary rocks are ____. A) inorganic B) detrital C) chemical D) biochemical E) carbonates

A sedimentary rock that consists of sediment grains bound by cement into a rigid framework is called _______. A) crystalline B) clastic C) biochemical D) organic E) recycled

_______ is an organic rock formed from the compression and alteration of plant remains such as leaves, twigs, and tree trunks. A) Crystalline B) Clastic C) Bioclastics D) Coal E) Recycled

___ is a sedimentary rock formed by the cementation of coarse angular fragments of rubble. A) Breccia B) Conglomerate C) Boulder rock D) Arkose E) Cataclastic

______ are sedimentary rocks deposited by direct precipitation of minerals from water. A) Hydro rocks B) Clastic rocks C) Chemical rocks D) Aquatic rocks E) Biologic rocks

A(n) ___ is sandstone containing a significant amount of feldspar. A) marble B) quartz sandstone C) graywacke D) shale E) arkose

A(n) ______ is sandstone in which more than 15% of the rock's volume consists of fine-grained matrix. A) quartz sandstone B) quartzite C) graywacke D) oolitic limestone E) arkose

A _____ is a layer of sedimentary rock with a vertical change in particle size, usually from coarse at the bottom to fine at the top. A) patterned bed B) cross bed C) sorted bed D) graded bed E) schist

_____ form(s) only in fine-grained sediments that are exposed to air. A) Cross beds B) Cleavage C) Mudcracks D) Bedding E) Ripples

Carbonate rocks contain the _____ ion as part of their chemical composition. A) CaO₃^2- B) CO₃^2- C) CaCO₃^2- D) limestone E) Carbonate rocks do not contain ions.

The two primary types of carbonate sedimentary rocks are ___ and dolostone. A) dolomite B) gypsum C) coal D) limestone E) sandstone

_______ sediments are deposited or precipitated as a result of the actions of organisms. A) Biochemical B) Pyroclastic C) Hyaloclastic D) Siliciclastic E) Calciclastic

_______ limestones are precipitated through the actions of organisms. A) Hyaloclastic B) Calciclastic C) Bioclastic D) Siliciclastic E) Pyroclastic

_____ are precipitated as a result of inorganic processes. A) Chalks B) Oolitic limestones C) Coals D) Calcic sandstones E) Fossiliferous limestones

____ limestones have a clastic texture. A) Fossiliferous B) Bioclastic C) Inorganic D) Chemical E) Oolitic

___ is a hard, compact, very fine-grained sedimentary rock composed entirely of silica. A) Tuff B) Chalk C) Chert D) Travertine E) Claystone

Rock salt is composed of the mineral ______. A) calcite B) trona C) dolomite D) halite E) gypsum

Peat is a brown lightweight unconsolidated deposit that ultimately can transform into ____. A) bogolite B) swampstone C) crude oil D) shale E) coal

The principle of ___ holds that, in a stack of horizontal layers the oldest layer is on the bottom and the layers become younger upward. A) supposition B) superposition C) superannualation D) original horizontality E) bedding

Oil and natural gas originate from _____ in marine sediments. A) peat B) the earth's interior C) organic matter D) coal E) comet impacts

___ are features found within sedimentary rock that formed during or shortly after deposition. A) Bedding planes B) Sedimentary structures C) Laminations D) Formations E) Turbidity currents

___ are polygonal patterns that form in very fine sediment as it dries. A) Ripple marks B) Cross beds C) Burrows D) Mud cracks E) Graded beds

Asymmetrical _____ are produced by current flowing in a single direction. A) wave marks B) ridge marks C) ripple marks D) mullion marks E) burrow marks

In sandstone, a thick bed will often consist of a series of thinner inclined beds called ____. A) laminations B) ripple beds C) graded beds D) cross beds E) tweed beds

Sedimentary rock on ____ will enable planetary geologists to one day unravel its history. A) the moon B) Jupiter C) Mars D) Mercury E) Io

Continental environments include all of the following except __. A) lake beds B) river beds C) glacial deposits D) coral reefs E) alluvial fans

A(n) ___ is a body of rock of considerable thickness that is large enough to be mappable and with characteristics that distinguish it from adjacent rocks. A) layer B) bed C) blanket D) formation E) epoch

A(n) ____ is a body of sediment deposited when a river flows into standing water, like a lake or sea. A) formation B) alluvial fan C) delta D) sandbar E) intrusive deposit

_____ are massive deposits of limestone. A) Turbidity flows B) Alluvial fans C) Deltas D) Reefs E) Lithosomes

______ forms from limestone when the calcium in calcite is partially replaced by magnesium. A) Gypsum B) Halite C) Chert D) Quartz E) Dolomite