Sedimentary Geology: Test 2

Front 1

Fluid flows of grain aggregates, moving primarily due to gravity.

Back 1

sediment-gravity flows

Front 2

Turbulence is a __________ mechanism.

Back 2

support

Front 3

In debris flows, the _________ of the matrix is its support mechanism.

Back 3

strength

Front 4

In grain flows, grain ________ is its support mechanism.

Back 4

collision

Front 5

In fluidized flows, _________ is its support mechanism.

Back 5

buoyancy

Front 6

In turbidity currents, _________ is its support mechanism.

Back 6

turbulance

Front 7

An example of a grain flow is an _________.

Back 7

rock avalanche

Front 8

An idealized material that behaves like a rigid mass under low levels of stress, but behaves like a Newtonian fluid above a critical amount of sheer.

Back 8

Bingham plastic

Front 9

Within the body of a flow, there is no movement of grains with respect to each other and behaves like a rigid mass.

Back 9

plug flow

Front 10

What is the formula for sheer stress (τ) in plug flows?

Back 10

τ = τc + μs (dU / dy)
τc = critical sheer stress
μs = viscosity of flow
dU/dy = change of velocity

Front 11

What initiates debris flows?

Back 11

Usually heavy rains or some other sudden, rapid flow where there is not a lot of vegetation and loose sediment.

Front 12

Where do debris flows usually happen?

Back 12

In deserts where there is loose soil and sediment with not a lot of vegetation.

Front 13

What is the Bagnold effect?

Back 13

When grains flow down and expand when they hit each other (called dynamic dilatancy)

Front 14

Collisional interaction of grains as they move relative to each other and expand as they flow.

Back 14

dynamic dilatancy

Front 15

The maximum slope angle (β) just before slope failure, or initiation of flow.

Back 15

angle of internal friction (φi)

Front 16

Formula for angle of internal friction?

Back 16

τ / σ = tan φi
τ = sheer stress
σ = upward-directed normal stress
φi = angle of internal friction

Front 17

When fluid is introduced into the sediment from below (i.e. baseflow in streams).

Back 17

fluidization

Front 18

When fluid is internal and moves up due to changes in packing (i.e. earthquake-induced sand volcanoes).

Back 18

liquidization

Front 19

What is an example of fluidization?

Back 19

groundwater moving up into streams through porous sediments, baseflow in streams

Front 20

What is an example of liquidization?

Back 20

sand volcanoes

Front 21

When silt and clay are suspended in air it is a __________.

Back 21

duststorm

Front 22

When snow is suspended in air it is a __________.

Back 22

snow avalanche

Front 23

When mud is suspended in water it is a ___________.

Back 23

turbidity current

Front 24

Vertical change in grain size with decreasing velocity.

Back 24

graded bedding

Front 25

Vertical change in sedimentary structures with decreasing velocity.

Back 25

Bouma sequence bedding

Front 26

Grain-supported rudite textures.

Back 26

orthoconglomerates

Front 27

Matrix-supported rudite textures.

Back 27

paraconglomerates

Front 28

Conglomerates can also be called _________.

Back 28

roundstones

Front 29

Breccias can also be called _________.

Back 29

sharpstones

Front 30

Rudites with one kind of grain.

Back 30

oligomictic

Front 31

Rudites with many kinds of grains.

Back 31

polymictic

Front 32

Rudites produced by weathering and sedimentation.

Back 32

epiclastic

Front 33

Epiclastic rudites formed outside of a basin.

Back 33

extraformational (extrabasinal)

Front 34

Epiclastic rudites formed inside a basin.

Back 34

intraformational (intrabasinal)

Front 35

Rudites produced by explosive volcanic eruptions.

Back 35

pyroclastic

Front 36

Rudites produced by tectonic stresses.

Back 36

cataclastic

Front 37

Rudites produced by collapse or karst-related structures.

Back 37

autoclastic

Front 38

Rudites produced by impacts.

Back 38

impact breccias

Front 39

A large-scale feature of a sediment or sedimentary rock, usually seen and best-studied in outcrop-scale view rather than hand sample.

Back 39

sedimentary structure

Front 40

What is a use of sedimentary structures?

Back 40

Using structures, you can infer the process and environment from which it was formed.

Front 41

One individual structure; individual element of a bed configuration.

Back 41

bed form

Front 42

The entire sedimentary structure.

Back 42

bed configuration

Front 43

Why are there bed configurations?

Back 43

We don't know exactly why they exist.

Front 44

When sediment gets finer as you go upward.

Back 44

fining upward sequence

Front 45

Structures formed at the time or very soon after deposition.

Back 45

primary structures

Front 46

What are some examples of primary structures?

Back 46

layering, cross-bedding, ripple marks, mud cracks

Front 47

Structures formed at some time (usually a long time) after deposition, typically during burial.

Back 47

secondary structures

Front 48

What are some examples of secondary structures?

Back 48

concretions, nodules, geodes

Front 49

Structures formed by the activity of organisms.

Back 49

biogenic structures

Front 50

What are some examples of biogenic structures?

Back 50

tracks, burrows, trails, trace fossils

Front 51

Can biogenic structures also be primary structures?

Back 51

Some people believe so.

Front 52

Formed under water.

Back 52

subaqueous

Front 53

Formed on land.

Back 53

subaerial

Front 54

Bedforms with straight crestlines, constant crest and trough elevations, and identical cross-sectional profiles at all locations along the crestline.

Back 54

2-D bedforms

Front 55

Bedforms with sinuous crestlines, sinuous troughs, or variable cross-sectional profiles along the crestline.

Back 55

3-D bedforms

Front 56

Bedforms that are planar.

Back 56

plane beds

Front 57

Dunes that migrate upstream (backwards).

Back 57

antidunes

Front 58

Antidune length is a function of flow _________.

Back 58

velocity

Front 59

When current erodes the bottom in some way and makes a mark.

Back 59

sole marks

Front 60

Marks made by an object.

Back 60

tool marks

Front 61

What are some examples of sole marks?

Back 61

flute casts, rill marks, current crescents

Front 62

What are some examples of tool marks?

Back 62

groove marks, brush marks

Front 63

When crystals grow in sediment (gypsum or ice) they form what bedding-plane structures?

Back 63

crystal imprints

Front 64

When soft sediment sinks into a soft layer of sediment below it.

Back 64

load casts

Front 65

A layer of constant lithology.

Back 65

bed

Front 66

The surface of a bed.

Back 66

bedding plane

Front 67

The thickness of sediment deposited under constant physical conditions; can be a series of beds.

Back 67

sedimentation unit

Front 68

What are some causes of bedding?

Back 68

variations in grain composition, grain-size, grain shape, fabric, or packing

Front 69

Lunate ripples are also called __________.

Back 69

barchan dunes

Front 70

Current ripples are _________.

Back 70

asymmetrical

Front 71

Oscillation ripples are __________.

Back 71

symmetrical

Front 72

When the tool approaches the sediment surface at a low angle and immediately bounces back into the current.

Back 72

bounce marks

Front 73

The tool approaches the sediment surface at a very low angle, with the axis of the tool inclined upcurrent, and is then lifted away by the current, producing a ridge of mud downcurrent of the mark.

Back 73

brush marks

Front 74

The tool reaches the sediment surface at a fairly high angle and is then lifted up and away by the current.

Back 74

prod marks

Front 75

The tool rolls over the sediment surface.

Back 75

roll mark

Front 76

The tool travels downcurrent with a saltating movement, hitting the sediment surface at near regular intervals.

Back 76

skip marks