STRATIGRAPHY AND SEDIMENTATION (DESERT)

Question 1

Definition of Dry based on precipitation

Answer 1

25 cm per (10 inches) per year

Question 2

Dryness

Answer 2

any situation where there is water deficiency

Question 3

Dry Climate

Answer 3

Climate in which yearly precipitation is less thanevaporation

Question 4

A marginal more humid variant of desert that represents a transition zone

Answer 4

Steppe or semiarid

Question 5

In which parts of the world are desert and steppe regions occur

Answer 5

Subtropics nd middle latitudes

Question 6

These are zone of high air pressure found usually in the dry regions of lower latitudes

Answer 6

Subtropical highs or Horse Latitude

Question 7

Describe the air movement in subtropical highs?

Answer 7

Air currents are subsiding and when air sinks, it becomes compressed and warmed

Question 8

These type of deserts are the ones situated in the deep interiors of large land masses or continents

Answer 8

Mid Latitude deserts and steppes

Question 9

What are the foremost barrier to moisture from the pacific in N.America?

Answer 9

1)Coast ranges
2) Sierra Nevada
3) Cascades

Question 10

What type of weathering is dominant in humid regions and provie evidence?

Answer 10

Chemical Weathering, slopes and rock edges are rounded and soil are well developed

Question 11

What type of weathering prevails in derserts and provide example

Answer 11

Mechanical Weathering, unaltered rock and mineral fragments

Question 12

What produces the rust-colored stain that tints some of the desert landscapes?

Answer 12

Oxidation of Iron Bearing Silicates

Question 13

Why is weathering in dry lands greatly reduced?

Answer 13

1) lack of moisture
2) lack of organic acids from decaying plants(carbonic acid)

Question 14

Streams that carry water only in response to specific episodes of rainfall

Answer 14

Ephemeral Streams

Question 15

American names for Ephemeral Streams

Answer 15

Wash or Arroyo

Question 16

Dry desert stream in arabia and north africa

Answer 16

Wadi

Question 17

Dry desert stream in South America

Answer 17

Donga

Question 18

Dry desert stream in India

Answer 18

Nullah

Question 19

This does most of the erosional work in deserts

Answer 19

Running Water

Question 20

Permament streams that do cross arid regions

Answer 20

Nile and Colorado

Question 21

Desert that is being traversed by Nile without having any single tributary

Answer 21

Sahara

Question 22

What is the main role of wind in deserts?

Answer 22

Transportation and deposition of sediment

Question 23

ridges and mounds of sediments formed primarily by wind action

Answer 23

Dunes

Question 24

This means discontinuous pattern of ephemeral streams that do not flow our of the desert to the ocean

Answer 24

Interior Drainage

Question 25

This pertains to the difference in elevation between high and low points in an area

Answer 25

Relief

Question 26

This forms when water heavily loaded with sediments emerged from the confines of the canyon and the runoff spread over the base of the mountains and loses velocity creating a cone of debris

Answer 26

Alluvial Fan

Question 27

Coalescing alluvial fans from adjacent canyons producing an apron of sediment

Answer 27

Bajada

Question 28

When streams flow across alluvial fans to the center of the basin converting the basin floor into a shallow lakes which lasts only few days or weeks

Answer 28

Playa lakes

Question 29

The dry flat bed left after evaporation of such lakes

Answer 29

Playa

Question 30

Playas that are encrusted with salts

Answer 30

Salt Flats

Question 31

Large bedrock knobs projecting above the sediment-filled basin

Answer 31

Inselberg

Question 32

Difference of wind from water erosion

Answer 32

1) Wind has lower capacity 2) Can spread sediment over larger areas as well as high into atmosphere

Question 33

Largest dust source in the world

Answer 33

N.Africa

Question 34

A disaster which happened in the 1930s which caused severe dust storm

Answer 34

Dust Bowl

Question 35

This is the lifting and removal of loose fine grained materials by wind

Answer 35

Deflation

Question 36

Shallow depressions which are the most noticeable results of deflation

Answer 36

Blowouts

Question 37

A stony veneer composed of coarse pebbels and cobbles thata re too large to be moved by the wind

Answer 37

Desert Pavement

Question 38

The process of cutting and polishing exposed rocks surfaces by windblown sand

Answer 38

Abrasion

Question 39

What is the limit of the vertical extend of wind abrasion

Answer 39

1m

Question 40

Extensive blankets of silts which were once carried in suspension

Answer 40

Loess

Question 41

mounds and ridges of sand from the winds bed load

Answer 41

Dunes

Question 42

Two primary sources of sediments that form loess

Answer 42

Stratified drift, deserts

Question 43

The most extensive deposits of loess on Earth

Answer 43

Noethern and western china

Question 44

River which got its name from the buff colored loess

Answer 44

Huang Ho or Yellow River

Question 45

Which areas of the world have loess formed from stratified drift

Answer 45

US and Europe

Question 46

Formation of dunes

Answer 46

1) Moving air encounters barrier 2) Wind sweeps around and over it leaving a shadow of more slowly moving air behind the obstacle an smaller zone of quieter air infront of the obstacle 3) Salting and sand grains rest in these ind shadows

Question 47

The steep side of a dune

Answer 47

Leeward

Question 48

the gently incline side

Answer 48

Windward

Question 49

In which side does sand move by saltation

Answer 49

Windward

Question 50

the leeward side of the dune

Answer 50

Slip face

Question 51

what is the maintaining angle of repose of the leeward side?

Answer 51

34 deg

Question 52

This forms when sand deposition forms layer inclined in the direction the wind is blowing

Answer 52

Cross Bedding

Question 53

A an example of cross bedding

Answer 53

Zion Canyon in Utah

Question 54

Factors affecting sand dune form and size

Answer 54

1) Wind Direction 2) Velocity 3) Availability of sand 4) Amount of vegetation

Question 55

Solitrary dunes shaped like crescents and with their tips pointing downwards

Answer 55

Barchan Dunes

Question 56

In what environment does it form?

Answer 56

Hard and flat ground Lack vegetation limited sediment supply

Question 57

Max annual migration rate of Barcham

Answer 57

15 m (50ft)

Question 58

Dunes that form a long rige that are separate by troughs and oriented at right angles to the prevailing wind

Answer 58

Transverse Dunes

Question 59

In what environment does it form?

Answer 59

Steady winds plenty sand supply sparse or lack vegetation

Question 60

Transverse dunes that form in arid regions where there is extensive amount of wavy sand

Answer 60

Sand sea

Question 61

Where do Transverse usually form

Answer 61

Coastal Dunes

Question 62

a relatively common form intermediate between isolated 61 and extensive waves of 64 which form scalloped rows of sand oriented at right angles to the wind which resembles series of brachans which have been positioned side by side

Answer 62

Barchanoid Dunes

Question 63

Example of Barchanoid

Answer 63

Gypsum Dunes, white sands, NM

Question 64

Long ridges of sand that form more or less parallel to the prevailing wind and where sand supplies are moderate

Answer 64

Longitudinal Dunes

Question 65

This dunes form where vegetation partially covers the sand and shape resembles that of barchan but tips are pointing into the wind direction

Answer 65

Parabolic dunes

Question 66

Envi in which 71 usually forms

Answer 66

Coastal where there are strong winds and abundant sand

Question 67

Usually three or four shar crested ridges diverge from a central high poing which are developed due to variable wind directions

Answer 67

Star Dunes

Question 68

Deserts where star dunes can be found

Answer 68

Sahara and Arabian