Understanding Deserts and Desertification: Types, Causes, and Characteristics, Quizzes of Geography

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TERM 1 Dry regions cover --% of Earth's land surface DEFINITION 1 Dry regions cover 30% of Earths land surface TERM 2 2 Climactic types of Dry regions DEFINITION 2 2 climactic types are commonly recognized: 1)Desert or arid 2)Steppe or semiarid TERM 3 Characteristics of a desert (2) DEFINITION 3 *Desert -less than 10 inches rainfall/yr -have a high enough sun angle so that evaporation exceeds precipitation TERM 4 4 Primary causes of desertification DEFINITION 4 (are these right?) 4 Primary causes of desertification 1) Cold Ocean Currents 2) Continentality 3) Sub-tropical highs 4) High mountains TERM 5 Dry lands are concentrated in 2 regions: DEFINITION 5 Dry Lands are concentrated in 2 regions: Subtropics Mid- Latitudes TERM 6 Subtropics - Characteristics (3) DEFINITION 6 Subtropics -Low-latitude deserts -In the vicinities of the Tropics of Cancer and Capricorn -Areas of high pressure and sinking air that is compressed and warmed IE: Sahara TERM 7 Mid-Latitudes - Characteristics (3) DEFINITION 7 Mid-Latitudes -Located in the deep interiors of continents - High mountains in the path of the prevailing winds produce a Rainshadow desert -Coastal deserts near cold ocean currents IE: Gobi Nevada - Rainshadow desert TERM 8 Desert Streams are said to be _________ DEFINITION 8 Desert Streams are said to be ephemeral TERM 9 Ephemeral DEFINITION 9 Carry water only during periods of rainfall TERM 10 Different names for desert streams DEFINITION 10 -Different names are used for desert streams in various regions -Wash & Arroya (western U.S.) -Wadi (Arabia & North Africa) TERM 21 Wind Erosion DEFINITION 21 -Wind Erosion Wind is relatively insignificant erosional agent with most erosion in a desert performed by the intermittent running water TERM 22 Mechanisms of Wind Erosion (2) DEFINITION 22 Mechanisms of wind erosion Deflation Abrasion TERM 23 Deflation DEFINITION 23 Deflation : Lifting of loose material Produces Blowouts (shallow depressions) and Desert Pavement (A surface of coarse pebbles and cobbles) TERM 24 Abrasion DEFINITION 24 Abrasion : Produces ventifacts (stones with flat faces) and yardangs (wind sculpted ridges) Limited in vertical extent TERM 25 Blowouts DEFINITION 25 Deflation produces Blowouts - shallow depressions TERM 26 Desert Pavement DEFINITION 26 Deflation causes Desert Pavement - A surface of coarse pebbles and cobbles TERM 27 Ventifacts DEFINITION 27 Abrasion produces Ventifacts -stones with flat faces TERM 28 Yardangs DEFINITION 28 Abrasion produces Yardangs - wind sculpted ridges TERM 29 Wind Deposits DEFINITION 29 Wind Deposits -Significant depositional landforms are created by wind in some regions TERM 30 2 Types of Wind Deposits: DEFINITION 30 2 Types of wind deposits: 1) Dunes 2) Loess TERM 31 Dunes (3) DEFINITION 31 Dunes -Mounds or ridges of sand -Often asymmetrically shaped -Windward slope is gently inclines and the leeward slope is called the slip face (very steep on the backside) TERM 32 5 Types of Dune Shapes DEFINITION 32 Barchan Transverse Longitudinal Parabolic Star dunes TERM 33 Loess (4 + Example) DEFINITION 33 Loess -Windblown silt -2 Primary sources are deserts and glacial outwash deposits -Extensive deposits occur in China and the central U.S. -Loess turns water yellow Black Blizzards during the Dust Bowl TERM 34 Out of the "Dust Bowl" came the DEFINITION 34 Soil Conservation Service (?) TERM 35 __% of Earth is covered by water DEFINITION 35 73% TERM 46 Wave Length DEFINITION 46 Wavelength - the horizontal distance between successive crests TERM 47 Wave Period DEFINITION 47 Wave period - the time interval between the passage of two successive crests form a given observation point TERM 48 Height, Length, and Period of a wave depend on... (3) DEFINITION 48 Height, length, and period of a wave depend on -Wind Speed (most important) - higher the wind Velocity, bigger the wave -Length of time wind has blown -Fetch - the distance that the wind has traveled across open water TERM 49 Wind Speed DEFINITION 49 Higher the wind velocity, bigger the wave TERM 50 2 Types of Waves DEFINITION 50 Types of Waves: 1) Waves of oscillation 2) Waves of translation TERM 51 Waves of Oscillation DEFINITION 51 Waves of oscillation -Wave energy moves forward, not the water itself -Occur in the open sea in deep water TERM 52 Waves of Translation DEFINITION 52 Waves of translation -Begins to form in shallower water when the water-depth is about on-half the wavelength and the wave beings to feel bottom, or drag-bottom -As the speed and length of the wave diminish, the wave grows higher -The steep wave front collapses and the wave breaks along the shore (white caps), Breaker Waves -Turbulent water advances up the shore and forms swash (landward rush of water) TERM 53 Wave erosion is caused by (2) DEFINITION 53 Wave erosion is caused by: -Wave impact and pressure - Abrasion by rock fragments TERM 54 Emergent Coasts DEFINITION 54 Emergent coasts -Develop bc of uplift of an area or a drop in sea level TERM 55 Features of an Emergent Coast (2) DEFINITION 55 Features of an emergent coast -Wave-cut cliffs (formed through retro gradation) -Wave-cut platforms (at the foot of the cliff) TERM 56 Wave Refraction is _____, and causes waves to _____ DEFINITION 56 Wave Refraction is the bending of a wave and causes waves to arrive nearly parallel to the shore TERM 57 Pacific Coast DEFINITION 57 -Relatively narrow beaches backed by steep cliffs and mountain ranges -A major problem is a significant narrowing of many beaches -Shoreline erosion varies considerably from one year to the next largely because of the sporadic occurrence of storms -COLD water (Never hurricanes TERM 58 Atlantic and Gulf Coast DEFINITION 58 -Development occurs mainly on the barrier islands (also called barrier beach or coastal barriers) -Barrier island face the open ocean -They receive the full forces of storms TERM 59 Submergent coast DEFINITION 59 Submergent coast -Caused by subsidence of land adjacent to the sea or a rise in seal level -Features of a submergent coast -Highly irregular shoreline -Estuaries : flooded river mouths TERM 60 Foreshore DEFINITION 60 Foreshore - constant swash and backwash activity TERM 71 Groin DEFINITION 71 A basic response to erosion problem it to build... Groin -Built to maintain or widen beaches -Constructed at a right angle to the beach to trap sand TERM 72 Breakwater DEFINITION 72 A basic response to erosion problem it to build... -Breakwater -Barrier built offshore and parallel to the coast -Protects boats from the force of large breaking waves TERM 73 Seawall DEFINITION 73 A basic response to erosion problem it to build... Seawall - Barrier parallel to shore and close to the beach to protect property -Stops waves from reaching the beach areas behind the wall TERM 74 Causes of tides DEFINITION 74 Causes of tides Tidal bulges are caused by the the gravitational forces of the Moon and to a lesser extent the Sun TERM 75 Tidal Range DEFINITION 75 Tidal range - Difference between high and low tides TERM 76 Spring Tides DEFINITION 76 Spring tides -Occur during new and full moons -Gravitational forces of the Moon and Sun are added together -Especially high and low tides -Large daily tidal range TERM 77 Neap Tides DEFINITION 77 Neap tides -Lowest range of each month -Occur during the first and third quarters of the moon -Gravitational forces of the Moon and Sun are offset (pulling in opposite directions, lowers tidal range) -Daily tidal range is least TERM 78 Other factors that influence tides DEFINITION 78 Other factors that influence tides -Shape of the coastline - Configuration of the ocean basin TERM 79 Tidal Cycles DEFINITION 79 Tidal Cycles: Mixed Tides- Semidiurnal- Diurnal - TERM 80 N.O.A.A. DEFINITION 80 N.O.A.A. publishes US tide charts; stands for the National Oceanographic Atmospheric Association TERM 81 Types of Tidal Currents DEFINITION 81 Types of tidal currents -Flood Current: advances into the coastal zonse as the tide rises (EROSION) -Ebb Current: seaward-moving water as the tide falls (CARRIES SEDIMENTS OUT TO SEA) TERM 82 Tidal Flats DEFINITION 82 Areas affected by the tidal currents are called tidal flats TERM 83 Tidal Deltas DEFINITION 83 Tidal deltas - depositional features deposited by the flood current; tide will push sand to form them TERM 84 True tidal waves are.. DEFINITION 84 True tidal waves are cause by incoming flood current TERM 85 Coral Reefs need. . DEFINITION 85 Warm, Clear & Shallow Water Coral Pollups -(these are the little creatures that secrete the coral reef) have a very narrow temp. range in which to live; require water in excess of 80* F and belower 90* F; Require clear water to allow enough sunlight to reach the reef; has to be shallow water, because light wont penetrate deep water;