Deck 6: Sedimentary Rocks the Archives of Earth History

Question 1

Sand dunes are most likely formed in a wet tropical environment.

Answer 1

False

Question 2

Pelagic clay deposits are associated with deep marine environments.

Answer 2

True

Question 3

Mud cracks indicate an episode of deposition and perhaps flooding followed by drier conditions.

Answer 3

True

Question 4

The mineralogical composition of sedimentary rocks is an indicator of the depositional environment.

Question 5

Current flow direction can be determined by cross-beds and some ripple marks.

Question 6

In bioturbation, most of the original sedimentary structures are preserved.

Question 7

Because wind has a limited capacity to transport sediment, wind deposits are poorly sorted.

Question 8

Cross-bedding can form via wind or water currents.

Question 9

Graded beds refer to sedimentary beds that show a decrease in grain size from bottom to top.

Question 10

Alluvial fans commonly occur in the marine environment.

Question 11

Fluvial deposits are considered part of the transitional sedimentary environment.

Question 12

The most important source rocks for fuels we use today are igneous rocks.

Question 13

The most common detrital sedimentary rocks are sandstones and mud rocks.

Question 14

Sedimentary structures form prior to lithification.

Question 15

Dense marine flows composed of a mixture of water and sediment are called turbidity currents.

Question 16

Rocks above and below a bedding plane may have different physical properties.

Question 17

A well-sorted sediment contains particles that are of about the same size.

Question 18

The chemical formula for dolomite is CaCO₃.

Question 19

Quartz, feldspar, and clay minerals are the most common constituents of sedimentary rocks.

Question 20

Most sedimentary rocks are deposited by water or underwater.

Question 21

Lagoons and reefs are sites of carbonate deposition.

Question 22

Fine-grained clays, silts and muds would always indicate a ____ environment.

A) low-energy
B) high-energy
C) shoreline
D) glacial
E) barrier island

Question 23

Pelagic oozes are derived from the shells of microscopic marine organisms.

Question 24

Large-scale cross-beds (greater than 10 ft. in height) commonly indicate a ___________ sedimentary environment.

A) lacustrine
B) desert dune
C) deltaic
D) fluvial
E) glacial

Question 25

From continent to deep-ocean basin, what is the order of offshore environments?

A) continental shelf, continental slope, continental rise
B) continental slope, continental shelf, continental rise
C) continental slope, continental rise, continental shelf
D) continental rise, continental slope, continental shelf
E) continental rise, continental shelf, continental slope

Question 26

Glacial deposits are composed only of particles of gravel size and larger.

Question 27

The degree to which detrital particles have had their sharp edges and corners smoothed off by abrasion is ____.

A) varve
B) cross-bedding
C) drift
D) sorting
E) rounding

Question 28

Till deposits are associated with ____.

A) lakes
B) glaciers
C) sand dunes
D) playa lakes
E) beaches

Question 29

____ would indicate deposition occurred in a high-energy environment.

A) Pelagic oozes
B) Conglomerates
C) Shales
D) Clay-rich rocks
E) Glacial till

Question 30

A long sand body more or less parallel with a shoreline but separated from it by a lagoon is a ____.

A) delta
B) barrier island
C) drift
D) tidal flat
E) varve

Question 31

A sedimentary layer in which grain size decreases from the bottom up is ____.

A) graded bedding
B) mud cracks
C) bioturbation
D) drift
E) till

Question 32

The churning of sediments by organisms that burrow through it is ____.

A) drift
B) rounding
C) sorting
D) bioturbation
E) varve

Question 33

At various times during Earth's history, the western half of the United States has been covered by an inland sea.

Question 34

Deltas form when streams or rivers encounter a standing body of water, such as an ocean or lake.

Question 35

Current ripple marks differ from wave ripple marks because ____.

A) current ripple marks flow in two directions
B) wave ripple marks flow in one direction
C) current ripple marks are common along the shoreline
D) current ripple marks are asymmetrical
E) wave ripple marks are asymmetrical

Question 36

The most common chemical sedimentary rock is ____.

A) sandstone
B) limestone
C) rock salt
D) coal
E) shale

Question 37

A deposit of sediment where a stream or river enters a lake or the ocean is called a(n) ____.

A) alluvial fan
B) braided stream
C) dune
D) tidal flat
E) d elta

Question 38

Limestone deposits most likely form in which environments?

A) alluvial fans
B) aeolian environments
C) fluvial environments
D) carbonate reefs
E) lagoons

Question 39

Turbidity currents deposit sediments in ____ beds with ____.

A) graded; fine sediments on top and coarse sediments on bottom
B) stratified; fine sediments on top and coarse sediments on bottom
C) graded; coarse sediments on top and fine sediments on bottom
D) cross; fine sediments on top and coarse sediments on bottom
E) cross; coarse sediments on top and fine sediments on bottom

Question 40

Deltas grow larger through the process of ____.

A) continental accretion
B) transitional wedging
C) marine encroachment
D) progradation
E) degradation

Question 41

____ are transitional environments because they ____.

A) Sand dunes; involve marine and continental processes
B) Barrier islands; involve marine and continental processes
C) Submarine fans; involve marine and continental processes
D) Glaciers; straddle the boundary between the mountains and the plains
E) Alluvial fans; straddle the boundary between the mountains and the plains

Question 42

The study of Earth's historical geography on a world-wide and local scale is ____________________.

Question 43

Dark-light couplets of sedimentary layers that represent yearly deposits in a glacial lake are called ____________________.

Question 44

Poorly sorted, nonstratified drift deposits are called ____________________.

Question 45

Sand deposits made by ____________________ are well sorted and have large (tens to hundreds of feet) cross-beds.

Question 46

Fluvial is a term referring to ____.

A) glaciers and glacial deposits
B) waves and wave deposits
C) turbidity currents and turbidites
D) river activity and river deposits
E) chemical processes and evaporites

Question 47

The gently sloping area adjacent to a continent is the ____________________.

Question 48

The three major depositional environments are ____________________, ____________________, and ____________________.

Question 49

Extensive burrowing by organisms that may destroy structures by thoroughly disrupting sediments is called ____________________.

Question 50

Prograding d elta deposits differ from turbidity current deposits because ____.

A) delta deposits coarsen upwards, with fine sediments on bottom and coarse sediments on top
B) turbidity current deposits coarsen upwards, with fine sediments on bottom and coarse sediments on top
C) delta deposits fine upwards, with coarse sediments on bottom and fine sediments on top
D) deltas are not subject to marine processes
E) turbidity currents are not subject to marine processes

Question 51

Polygonal forms in clay sediments generated by repeating cycles of wet and dry are ____________________ ____________________.

Question 52

The transitional depositional environment that involves progradation is a(n)_____________________.

Question 53

In a well-sorted rock, ____.

A) all grains are about the same size
B) all rocks are about the same size
C) all grains have cross-bedding
D) grains are graded
E) there are no signs of bioturbation

Question 54

An example of a biogenic sedimentary structure is ____.

A) concretion
B) trace fossil
C) organic formation
D) lagoon
E) pelagic ooze

Question 55

A(n) ____________________ is a long accumulation of abundant sand that lies offshore and is separated from the mainland by a lagoon.

Question 56

A sample of deep-sea sediments would be expected to contain ____.

A) sand
B) sand and ooze
C) fine-grained clays and ooze
D) limestone
E) coral reefs

Question 57

The majority of sediment transported across the continental shelf travels through ____.

A) lagoons
B) island arcs
C) subduction trenches
D) back-arc basins
E) submarine canyons

Question 58

Graded bedding forms when ____.

A) erosion planes off a portion of the sea bottom
B) sediment is deposited on a steep slope or grade
C) turbidity currents deposit first coarse-grained sediment then fine-grained sediment
D) cross-bedding is truncated at top and curved (or tangential) at bottom
E) turbidity currents deposit first fine-grained sediment then coarse-grained sediment

Question 59

Analysis of ____ is the best way to determine depositional environments.

A) textural evidence
B) compositional evidence
C) the present environment
D) sedimentary structures
E) geometrical configurations

Question 60

Herringbone crossbeds develop in tidal flats because ____.

A) alternating cycles of wet and dry conditions
B) a large supply of fine sediment is available
C) a large supply of coarse sediment is available
D) tidal inflows and outflows
E) sediment frequently washes over

Question 61

Compare and contrast the various types of depositional environments in which evaporite deposits form. How do these deposits differ?

Question 62

Compare and contrast the sediments deposited in continental, transitional, and marine environments. Give specific examples of these sediment types and the environments where they commonly form.

Question 63

Compare and contrast sediments deposited from the coastline to the deep marine environment. Give examples of the sedimentary rocks that form by the lithification of these sediments.

Question 64

Discuss why the analysis of sedimentary environments is important in the study of historical geology. Provide some examples of how sedimentary rocks can indicate specific environments of deposition.

Question 65

Crossbeds and current ripple marks can both indicate the direction of a current. Explain how crossbeds and current ripple marks differ and the types of environments you would expect to find them in.

Question 66

Describe and discuss the carbonate deposits expected in different parts of an organic reef environment.

Question 67

Explain how fossils, and especially microfossils, can be used to help determine ancient depositional environments.

Question 68

Discuss the use of fossils to determine the depositional environment of a sedimentary stratum. Give examples of some fossils that imply a specific environment.

Question 69

Describe and discuss the sedimentary deposits that you would expect in a deltaic environment.

Question 70

Imagine you are a geologist standing in front of a large outcrop of sandstone, shale, and limestone layers. It is your job to determine the depositional environment(s) and paleogeographic history of the area. What are four pieces of information needed to make a determination, and how will those pieces of information help you make a determination?