Geology Chapter 6

Which of the following sedimentary features can each be used to determine paleocurrent directions?

ripple marks and cross stratification

Which one of the following is not a chemical sedimentary rock or evaporite?

shale

A cherty limestone would contain which major constituents?

silica; calcite

Which of the following sedimentary features would typically be found in shales but not in sandstones?

mud cracks

Which of the following is not a type of limestone?

Arkose

What is the main difference between conglomerate and a sedimentary breccia?

Breccia clasts are angular; conglomerate clasts are rounded.

Detrital grains of which minerals are extremely rare in detrital sediments?

Calcite

_____is a form of calcium carbonate.

Chert

_____is not a common cementing agent for sandstone.

Fluorite

_____is the most common type of chemical sedimentary rock.

Limestone

_____cement produces bright-red and yellow colors in some sandstone.

iron oxide

Nonclastic textures are common in which of the following sedimentary rocks?

limestones

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

True

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

True

_____sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock.

arkosic

What is probably the single most important, original, depositional feature in sedimentary rocks?

bedding or stratification

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

evaporite minerals are less soluble than quartz and calcite

Which of the following best describes bedded gypsum and halite?

evaporites; chemical, sedimentary rocks

Coal beds originate in______.

freshwater coastal swamps and bogs

Detrital sedimentary rocks are classified based on the _____.

grain sizes of the detrital particles

Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas?

high porosity

Which statement concerning sedimentary rocks is not true?

they were originally deposited at depths below the bottom of the sea

Which of the following applies to the basic constituents of halite, gypsum, and sylvite?

transported as dissolved ions, deposited by evaporation

Many limestones are of biochemical origin.

true