Chapter 7 - Sedimentary Rocks

Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks?

Evaporate minerals are more soluble than calcite and quartz.

Which of the following is not a type of limestone?

arkose

Which type of limestone consists mainly of tiny, marine fossils composed of calcite?

chalk

Coal beds originate in ________. channels of fast-moving streams Correct Answer freshwater coastal swamps and bogs shallow lakes in a dry, desert region deep, marine basins below wave action

freshwater coastal swamps and bogs

Red, brown and yellow sandstones are cemented by oxides of ________.

iron

_______ cement produces bright-red and yellow colors in some sandstone. Correct Answer Iron oxide Quartz Calcite Clay

iron oxide

Nonclastic textures are common in which of the following sedimentary rocks? sandstones boulder breccias cherty conglomerates Correct! limestones

limestone

Which variety of limestone consists mainly of sand-sized, mostly spherical grains of calcium carbonate precipitated in shallow, marine waters?

oolitic

What is the most abundant mineral in detrital sedimentary rocks?

quartz

______, a common mineral found in igneous rocks, is the most abundant mineral in detrital sedimentary rocks.

quartz

A cherty limestone would contain which major constituents? Correct Answer silica, calcite iron oxide, calcite clay minerals silica, iron oxide

silica calcite

What are the three, most common, cementing agents for sandstones?

silica, calcite, iron oxide

Which property of sediment describes the range of different grain sizes in a detrital sedimentary rock?

sorting

What is the most characteristic, original, depositional feature preserved in sedimentary rocks?

stratification

Which of the following applies to the basic constituents of halite, gypsum, and sylvite? transported as detrital mud; deposited by evaporation transported as dissolved ions; deposited as detrital mud transported and deposited as mud-sized particles Correct Answer transported as dissolved ions; deposited by evaporation

transported as dissolved ions; deposited by evaporation

______ is a form of calcium carbonate. Correct! Travertine Chert Lignite Gypsum

travertine

A feldspar-rich sandstone is called an arkose.

true

Detrital sedimentary rocks are classified according to clastic particle size; chemical sedimentary rocks are named according to the most abundant minerals.

true

Detrital sedimentary rocks have clastic textures.

true

Peat is thought to be the original material from which coals are formed.

true

Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometers of rock (first percentage). Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage)? 3.5% and 100% Correct Answer 5% and 75% 85% and 100% 65% and 10%

5% and 75%

What is the main difference between a conglomerate and a sedimentary breccia? Correct Answer Breccia clasts are angular; conglomerate clasts are rounded. Breccia clasts are the size of baseballs; conglomerate clasts are larger. A breccia is well stratified; a conglomerate is poorly stratified. Breccia has a compacted, clay-rich matrix; conglomerate has no matrix.

Breccia clasts are angular; conglomerate clasts are rounded.

Detrital grains of which mineral(s) are extremely rare in detrital sediments? Why? Correct Answer Calcite; it is soft and relatively soluble. Clays; they are rare in soils and regolith. Feldspars; they occur only in granites. Quartz; it is very hard and insoluble.

Calcite; it is soft and relatively soluble.

Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks? Evaporate minerals are more soluble than quartz and less soluble than calcite. Correct Answer Evaporate minerals are more soluble than calcite and quartz. Evaporate minerals, quartz, and calcite all have the same relative solubility. Evaporate minerals are less soluble than quartz and calcite.

Evaporate minerals are more soluble than calcite and quartz.

Which statement concerning sedimentary rocks is NOT true? Correct! They were originally deposited at depth below the bottom of the sea. They are composed of particles and constituents derived from weathering and erosion of other rocks. They probably show some evidence of stratification. They may contain fossils that provide clues about ancient life forms.

They were originally deposited at depth below the bottom of the sea.

graywacke is ________. Correct! a sandstone with the sand grains embedded in a clay-rich matrix a limestone with abundant, sand-sized, quartz grains a dark, organic-rich, chemical sedimentary rock containing small crystals of halite a dark-gray, calcite-rich mudstone or shale containing pyrite

a sandstone with the sand grains embedded in a clay-rich matrix

What is the general name for microcrystalline quartz in sedimentary rocks?

chert

Which major component of detrital sedimentary rocks only rarely occurs as a primary mineral in igneous rocks?

clay

Which major component of detrital sedimentary rocks only rarely occurs as a primary mineral in igneous rocks? ferromagnesian minerals carbonates Correct Answer clays quartz

clays

_______ is composed mainly of lithified, organic debris that accumulated in ancient, heavily forested swamps. Correct!

coal

Sandstones are lithified mainly by cementation. What is the major process involved in the lithification of shales?

compaction

What term describes the complex, original stratification pattern seen in sandstones deposited in ancient sand dunes?

cross-bedding

Which of the following best describes bedded gypsum and halite?

evaporates

The sedimentary rocks, salt and gypsum, are deposited by what process?

evaporation

Boulder conglomerates suggest deposition by strong winds in a desert.

false

Chalk, coquina, and ancient coral reefs are primarily composed of microcrystalline quartz.

false

Clastic particles in a sedimentary breccia are rounded and are about the same size as fine-grained sand.

false

Graywacke sandstones are typically better sorted than sandstones lithified from ancient beach sands.

false

Mud cracks in a shale or mudstone indicate that the mud or clay was deposited in deep waters of an offshore marine environment.

false

The chemical sedimentary rock, conglomerate, is composed of gravel-size, rounded, calcite oolites. True Correct! False

false

________ is not a common cementing agent for sandstones. Calcite Iron oxides Correct Answer Fluorite Quartz

fluorite

Flint, chert, and jasper are microcrystalline forms of ________. calcite (CaCO₃) halite (NaCl) Correct! quartz; (SiO₂) hematite (Fe₂O₃)

quartz; (SiO₂)

Which one of the following is not a chemical sedimentary rock or evaporite? cherty dolostone oolitic limestone bedded gypsum Correct Answer shale

shale

Oolitic limestone is most likely to form in what type of depositional environment? deep, marine waters below most wave action acidic, organic-rich waters in freshwater swamps and bogs Correct! shallow, clear, marine waters with vigorous current activity quiet, muddy, lagoons and bays

shallow, clear, marine waters with vigorous current activity

The mineral dolomite, which is the major mineral of the sedimentary rock dolostone, is a carbonate of calcium and magnesium. Correct Answer

true

Water is gradually expelled from compacting clay and mud sediments.

true