LANDFORMS EXAM 3

Capacity

- Floods occur when a river overflows it banks, i.e., its channel capacity is exceeded. -CAPACITY is a measure of the total amount of SUSPENDED LOAD that a river can carry. It is a direct function of the water velocity and Capacity increases to the 5th power of the proportional increase in velocity. - Note : doubling velocity increases capacity by 32 times

Floodplain

- a flat or nearly flat land adjacent a river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge. -features:Meanders, Meander scars, Oxbow lakes, Terraces, Point bar, Cut bank, Natural levee Flood plain

Energy, river

- a river's energy comes from GRAVITY, thus the higher a rivers elevation, the greater its energy --USE OF ENERGY - the energy is used up in WORK cutting the channel, transportation of load. -VELOCITY, the speed of the current, is a measure of river energy, the faster the water the more the energy.

Stylolites, Tennessee marble

- are dark zigzag lines that run through limestone and marble that form where rocks are deeply buried and the pressure great. The passage of water along surfaces within the limestone dissolves the calcite but leaves behind dark insoluble minerals. These are commonly seen in decorative limestone and marble wall facing.

Drainage patterns

- may be controlled by bedrock or topography. - formed by the streams, rivers, and lakes in a particular drainage basin. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land.

Interior drainage

- the Basin and Range region, largely in Nevada, is a region of INTERIOR DRAINAGE, wherein rivers do not reach the sea

Spillway

-(floodways) -Morganza Spillway -Bonnet Carre spillway

Arkansas desert

-10,000 to 20,000 years ago central Arkansas was a cold desert. The deflation of glacial outwash removed the fines (later deposited to form the loess under Memphis) and left sand dunes like this one near Newport.

Arkansas Dunes

-20,000 years ago Arkansas was a cold desert on the southern margin of the Laurentide Ice Sheet (more about it under the desert and glacier topics). -Computer models of ancient climates (paleoclimatology) need to be constrained with facts. -What was the wind direction 20,000 years ago when the glaciers began to retreat? -Paleowind direction estimates based on loess suggest a west wind in east Arkansas and west Tennessee 20,000 years ago -Newport, AR: 10,000 to 20,000 years ago central Arkansas was a cold desert. The deflation of glacial outwash removed the fines (later deposited to form the loess under Memphis) and left sand dunes like this one near Newport. -Diaz, Arkansas: Transverse sand dunes

Delta

-A DELTA is a landform at the mouth of a river, where the river flows into an ocean, lake, or reservoir. Deltas form from deposition of sediment carried by a river as the flow leaves its mouth. -A delta is a body of sediment deposited at the mouth of a river where a river meets a standing body of water. -Nile River Delta

Desert

-A DESERT is a region that receives extremely low precipitation, 1) less than enough to support growth of most plants. 2) areas with an average annual precipitation of less than 10 in per year (some authors prefer 4 or 6 inches) 3) a region where more water is lost by evapotranspiration than falls as precipitation. -Deserts may be hot or cold -Taklimakan Desert, central Asia is a "COLD" desert

Knickpoint

-A NICKPOINT is an abrupt change in the longitudinal profile of a stream. There are several causes for nickpoints including change in base level. The channelization of the Mississippi River and its subsequent increase in velocity has caused KNICKPOINT MIGRATION in the Wolf River.

Wing Dams

-A WING DAM is a man made barrier that extends partway into a river. These structures force water into a fast-moving center channel which reduces sediment accumulation in the channel while slowing water flow and trapping sediment near the riverbanks. The Mississippi River has thousands of wing dams which were originally constructed to reduce the amount of dredging required when the main navigation channel was maintained to at least 4½ ft (1.37 m). Since that time, additional dams doubled the depth of the navigation channel to 9 feet (2.75 m).] -Wing dams are visible in the Mississippi River at low water upstream from the DeSoto Bridge. -Wing dams are visible in the Mississippi River at low water upstream from the DeSoto Bridge.

Bajada

-A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial fan. -BAJADAS are formed by the lateral merging and blending of a series of alluvial fans along a mountain front. They extend from the base of a mountain range out onto the valley floor of an inland basin.

Sinkholes

-A sinkhole (aka cenote) is a natural depression in the Earth's surface caused by the chemical dissolution of carbonate rocks. Sinkholes vary from 4 to 2,000 ft in diameter. Sinkholes may be formed gradually or suddenly and are found worldwide. -Over time cave breakdown results in a sudden cave ceiling collapse forming a sinkhole. Many sinkholes occur naturally while others are the result of human activity. -Human activity such as draining groundwater can open cavities and broken pipes can erode otherwise stable subterranean sediments. Urban sinkholes, up to hundreds of feet deep have formed and consumed parts of city blocks, sidewalks and entire buildings -SINKHOLES form when the collapse reaches the surface -There are thousands of sinkholes in Tennessee, most commonly in the Central Basin -vary in size -Are most common in warm humid climates -Central Florida is riddled with sinkholes -Also occur in relatively dry regions -"sinkholes" refer to areas where bedrock is solid but has been eaten away by groundwater -. Sinkholes may be formed gradually or suddenly

Mississippi R. evolution

-A. 30,000 years ago the Mississippi- Missouri system flowed west of Crowley's Ridge and was braided. The Ohio was also braided and flowed between CR and CB. -B. 20,000 years ago the Mississippi- Missouri system breached the Bell City Gap and began to flow both east and west of Crowley's Ridge -C. 15,000 yr BP the Miss and Missouri system flowed both east and west of CR parallel to the Ohio River. -D. 10,000 years ago the Mississippi River breached Crowley's Ridge at Thebes Gap -E. 9,000 years ago the Miss. and Ohio flowed parallel between Crowley's Ridge and the Chickasaw Bluffs. -F. 8,000 years ago the Mississippi. River beheaded the Ohio and changed to a meandering style

Atacama Desert

-ATACAMA DESERT, Chile -Atacama Desert is the driest place in the world. The average rainfall is just 1 millimeter (0.04 in) per year. Some weather stations in the Atacama have never received rain.

Tibet Plateau

-Above India, right above Himalayas west of China. -Highest region in the world

River Terrace

-Alluvial terraces are abandoned floodplains left behind as a river down cuts its channel toward sea level. -The UPLAND COMPLEX is a terrace gravel formed by the Pliocene ancestor of the modern Mississippi River (PMR). The Upland Complex underlies the loess on the Chickasaw Bluffs and Crowley's Ridge and is an important source of construction gravel and sand.

Beach dune

-Although we associate dunes with deserts they are also common along shores. The onshore wind picks up sand on the beach and deposits it in back beach dunes. -Dunes are not exclusively found in deserts. -Dunes form where wind sweeps sand off a beach

Oxbow lake

-An OXBOW LAKE IS A U-SHAPED BODY OF WATER formed when a wide meander from the main stem of a river is cut off to create a lake. This landform is called an oxbow lake for the distinctive curved shape, named after part of a yoke for oxen. - OXBOW LAKES form where meandering rivers abandon a meander (locally called horseshoe lakes). -Between 1880 and 1900 Lake Goodenough, an OXBOW LAKE, formed when the Missouri River formed a CUTOFF. -Horseshoe Lake, Arkansas is an oxbow lake in geomorphology terminology.

Alluvial fan

-An alluvial fan is a fan- or cone-shaped deposit of sediment built up by streams or debris flows. These flows come from a single point source at the apex of the fan, and over time move to occupy many positions on the fan surface. Fans are typically found where a canyon draining mountainous terrain emerges out onto a flatter plain. -Alluvial fans require flowing water and their presence on Mars came as a surprise. Their origin is controversial but at least some are geologically young. The one labeled 4 is dated at ca. 1.25 Ma on the basis of the meteor impact density.

Cross-beds

-An arrangement of beds or laminations in which one set of layers is inclined relative to the others. -FORMATION BY WIND -Steeper side downwind -TYPES: Cascade face, Lee face, Slip face

Saltation load

-BED LOAD - SALTATION - SAND SIZE GRAINS -SALTATION is the Bed load TRANSPORT OF SAND-SIZED particles in short hops close to the ground. -SALTATION is the movement of sand-sized particles in short hops close to the ground. This is why a beach blanket gets covered with sand on a windy day. -Undercut ledges are a consequence of sand-sized grain saltation. Saltation sand also abrades fence posts and auto finishes

Barchan dune

-Barchan dunes are crescent shaped with "horns" pointing down wind. -Atypical barchans: Sculpted by winds that consistently blow from east to west, barchans migrate across an ancient seafloor, rising about six feet and spreading 20 to 30 feet across. The strange shape is unexplained. -on Mars

Butte and mesa

-Butte - an isolated hill with steep sides and a flat top - smaller than a mesa -Mesa - an isolated hill with steep sides and a flat top - larger than a butte -A BUTTE is a conspicuous isolated hill with steep, often vertical sides and a small flat top. They are common landforms on the Colorado Plateau -Merrick's Butte in Monument Valley, Utah -A MESA, Spanish for table, is an elevated area of land with a flat top and sides that are usually steep cliffs. It is a common landform of arid environments, particularly the COLORADO PLATEAU of the southwestern United States..

Cold Desert

-COLD DESERTS are common. ANTARCTICA and the ARCTIC are deserts!!

Competence

-COMPETENCE is a measure of the LARGEST PARTICLE a stream can carry at a given velocity. It is function of velocity to the sixth power:

Deflation

-DEFLATION = WIND EROSION -DEFLATION is the process of removal of sand and silt sized particles from an area by wind. -Deflation leaves coarse, gravel-sized particles behind forming Desert armor, aka Desert pavement - Deflation removes of finer sediment -DEFLATION = SUSPENSION TRANSPORT

Desertification

-DESERTIFICATION is the extreme deterioration of land in arid and dry sub-humid areas due to loss of vegetation and soil moisture. Desertification results chiefly from human activities influenced by climatic variations. It is principally caused by overgrazing, overdrafting of groundwater and diversion of water from rivers for human consumption and industrial use. All of these processes fundamentally driven by overpopulation. - U.S. DESERTIFICATION is modest because our deserts are not large and population migration is largely into cities rather than agricultural areas. -Replacement of drought resistant wild grass (right) with extensive root systems with domesticated plants with relatively shallow root systems (left) that could no withstand multiyear dry spells was part of the problem

Desert armor

-Desert armor, aka Desert pavement -DESERT ARMOR (pavement) is a one pebble thick layer of gravel on desert surfaces formed by wind DEFLATION -When DESERT ARMOR is breached by human activity, deflation begins anew with the addition of dust to the atmosphere.

Hot desert

-Deserts may be hot or cold

Rejuvenation

-ENTRENCHED MEANDERS form when meandering rivers are REJUVENATED by regional uplift

Climate

-FLOOD PLAIN REGULATION: Changing climate and human factors change flood levels.

Floodway

-FLOODWAYS ("spillways") bypass excessive flood water into adjacent rivers. Floodways located north of Memphis (New Madrid, Oak Donick) divert the Mississippi into the St. Francis River. -Floodways north of New Orleans (Bonnet Carre, Morganza, and Old River) divert it into the Atchafalaya River or Lake Ponchitrain.

Flood, 2011

-HISTORIC MISSISSIPPI RIVER LEVELS: -Bank full is +34 feet at Memphis, over this the river is in flood and certain legal authority can be invoked. -FLOOD! 48.0 ft in May 2011

Flash flood

-Heavy rainfall drains out of deep narrow canyons in adjacent high mountains onto the desert floor. Such floods are very violent as there is little in the way of vegetation to slow or impound the water.

Impoundment

-IMPOUNDMENTS are lakes formed by dams, for example ARKABUTLA Lake, SARDIS Lake, ENID Lake. -They control runoff by trapping it during periods of heavy rainfall, then later releasing it when conditions permit. They also trap sediment thus reducing the load thereby speeding up the river.

Ground water

-Implicit in the discussion of ground water resources is the storage of the water in clastic rocks, SANDSTONE for the most part.

Arkabutla Lake

-Inset of the modern Mississippi River superposed on Arkabutla. -Meander scars of the Upland Complex show best on DEM maps. They are much larger than the meanders of the present river.

Lag time

-LAG TIME is the time between heavy rain and a flood crest. Urbanization decreases lag time

Loess

-LOESS is a clastic sediment formed by the accumulation of wind-blown SILT-SIZED dust. -10% of the Earth's land area is covered by loess. -Loess deposits form the Chickasaw Bluffs. -LOESS - deposit of wind suspension load -LOESS - wind deposited silt -Despite being unconsolidated, loess forms vertical cliffs because the tiny particles adhere to each other with bonds stronger than the force of gravity. -CHINA LOESS is much older and thicker than U.S. loess -Iowa has the same loess as the loess that forms the Chickasaw Bluffs. -LOESS - dust storms deposit SILT-SIZED grains -Loess is intimately tied to glaciers. -Loess forms the Chickasaw Bluffs and caps Crowley's Ridge

Great Salt Lake

-Lake Bonneville was a prehistoric pluvial lake that covered much of North America's Great Basin region. It covered much of present-day Utah. Formed about 32,000 years ago, it existed until about 14,500 years ago.

Basin and Range

-Largely in Nevada, the mountainous desert of the Basin and Range is dominated by N-S trending mountains 50 to 100 miles long and about 5 miles wide. Intermountain basins are filling with sediment derived from erosion of the mountains. -INTERMOUNTAIN BASINS-Basin and Range, Nevada - the Basin and Range region, largely in Nevada, is a region of INTERIOR DRAINAGE, wherein rivers do not reach the sea

Parabolic dune

-Like Barchan Dunes Parabolic Dunes are crescent shaped but the "horns" point upwind, the direction from which the wind comes.

Calcite

-Limestone is made of the mineral calcite. Calcite dissolves very rapidly in acid. Consequently limestone dissolves very rapidly.

Limestone

-Limestone is made of the mineral calcite. Calcite dissolves very rapidly in acid. Consequently limestone dissolves very rapidly. -LIMESTONE SOLUTION is common in regions of LIMESTONE BEDROCK where the climate is warm and humid -LIMESTONES tend to fracture.

Cumberland Cavern

-Located in McMinnville, TN, Cumberland Caverns, with a surveyed length of 27 miles, is the 18th longest cave in the United States. -The cave is privately owned and open to the public for a fee.

Chickasaw Bluffs

-Loess deposits form the Chickasaw Bluffs. -LOESS underlies the Chickasaw Bluffs

Crowley's Ridge

-Loess forms the Chickasaw Bluffs and caps Crowley's Ridge -LOESS caps CROWLEY'S RIDGE

Longitudinal dune

-Longitudinal dunes (aka Seif dunes) have their long axis parallel to average wind direction. Longitudinal dunes form where winds blow from alternating quarters. -aka SEIF DUNE -Elongated, sharp-crested seifs, named after the Arabic word for sword, take shape in regions with moderate sand and shifting winds.

Great Flood, 1927

-MISSISSIPPI RIVER: -FLOOD!!! 48.8/49 ft in April, 1927 ("the Great Flood") -Combination of natural and man-made causes -The 1927 flood began when heavy rains pounded the central basin of the Mississippi in the summer of 1926. By September, the Mississippi's tributaries in Kansas and Iowa were swollen to capacity. The Mississippi River broke out of its levee system in 145 places and flooded 27,000 square miles, an area 50 mi wide and more than 100 mi long up to a depth of 30 feet (10 m). The flood caused over $400 million in damages and killed 246 people in seven states. -Remember: The Mississippi river near Memphis is declared to be in flood when it exceeds 34 ft above zero on the Memphis Gauge. -Breached levee during the Great Mississippi flood of 1927

30,000 years ago

-MISSISSIPPI RIVER: -BRAIDED RIVER DEPOSITS ~30,000 years old

10,000 years ago

-MISSISSIPPI RIVER: -MEANDERING RIVER DEPOSITS <10,000 years old

Ohio River

-MISSISSIPPI-MISSOURI-OHIO RIVER drainage basin is over a million square miles -Most of the WATER comes from the Ohio River, most of the SEDIMENT comes from the Missouri River

Mars rivers

-Mars is the only planet besides Earth that shows evidence of water erosion and deposition -Convincing evidence of surface flow on Mars: delta and meander scars -False-color image of gully channels in a crater in the southern highlands of Mars, taken by the High Resolution Imaging Science Experiment camera on the Mars Reconnaissance Orbiter. -Martian Alluvial Fan: Alluvial fans require flowing water and their presence on Mars came as a surprise

Meandering river

-Meanders appear in the geologic record about the time land plants appear suggesting that the soil binding action of plants is a factor in meander formation. -A meander is a bend in a sinuous river. A meander is formed when the moving water in a stream erodes the outer banks and widens its valley.

Dust bowl era

-Nevertheless, the DUST BOWL storms of the 1930's were the worst environmental disaster in U.S. history. Vast areas of Kansas, Oklahoma, Texas, Nebraska, and neighboring states were devastated and essentially depopulated by the massive failure of farms and their dependent infrastructure. The book "The Grapes of Wrath" and the subsequent movie dramatized the social impacts. -The cause of the dust bowl conditions was a combination of geology, climate, culture, and economics.

Sandhills Nebraska

-Not all dune areas are deserts NEBRASKA SANDHILLS REGION...dune topography stabilized by grass -The Sandhills is a region of prairie grass-stabilized sand dunes in north-central Nebraska, covering just over one quarter of the state. Paleoclimate data suggest that the Nebraska Sandhills had active sand dunes as recently as the Medieval Warm Period, about 950 to 1200 AD

Breakdown

-Over time cave breakdown results in a sudden cave ceiling collapse forming a sinkhole. -happens when: after water drains from a cave the unsupported ceilings may collapse.

Intermontane basin

-PLAYA LAKES form where water is trapped in intermontane desert basins. -A lowland between mountains

Playa Lake

-PLAYA LAKES form where water is trapped in intermontane desert basins. The lakes eventually evaporate to dryness leaving behind level surface encrusted with evaporate salts called PLAYAS.

Paleowinds

-Paleowind direction estimates based on loess suggest a west wind in east Arkansas and west Tennessee 20,000 years ago

Peoria Loess

-Peoria Loess, is Holocene, circa 22,000 to 10,000 years BP.

Upland Complex gravel

-Pliocene Miss R. deposited Upland Complex -The age of Upland Complex gravel and sand deposited by the PMR was determined using cosmogenic isotopes

Polar desert

-Polar - ice sheets -antartica -areas in Antarctica and the Arctic ice sheet that have dry and cold climate conditions

Atchafalaya River

-QUESTION: Why doesn't the Mississippi River abandon its present channel and flow down the Atchafalaya channel (a natural occurrence called beheading). ANSWER: The Corps of Engineers wont let it. During normal water the Corps allows 30% of the Mississippi to flow down the Atchafalaya River -Floodways north of New Orleans (Bonnet Carre, Morganza, and Old River) divert it into the Atchafalaya River or Lake Ponchitrain. -Water flows through 4 open gates of the Morganza spillway into the Atchafalaya River.

Running water

-RUNNING WATER is the dominant agent of erosion in deserts, not wind.

bed load

-SALATATION load, aka BED LOAD is in contact with the bottom of the river, the particles roll and jump (saltation) along the bottom. Sand and gravel size particles move by this mechanism. The Mississippi River transports a bed load of 40,000,000 tons/yr into the Gulf of Mexico.

Bed load (sand)

-SALTATION - bed load -Undercut ledges are a consequence of sand-sized grain saltation. -Saltation sand also abrades fence posts and auto finishes. -BED LOAD - SALTATION - SAND SIZE GRAINS -SALTATION is the Bed load TRANSPORT OF SAND-SIZED particles in short hops close to the ground. -SALTATION is the movement of sand-sized particles in short hops close to the ground. This is why a beach blanket gets covered with sand on a windy day.

Dune

-SAND DUNES are asymmetrical hills of sand. They form as sand SALTATES up the windward slope and cascades down the lee (downwind) face to form the cross beds typical of sand dune deposits in sedimentary rocks. -The downwind face of a dune is the steep face -Barchan dunes are crescent shaped with "horns" pointing down wind. -Like Barchan Dunes Parabolic Dunes are crescent shaped but the "horns" point upwind, the direction from which the wind comes. -Longitudinal dunes (aka Seif dunes) have their long axis parallel to average wind direction. Longitudinal dunes form where winds blow from alternating quarters. -Transverse dunes have their long axis perpendicular to wind direction. -Star dunes form where winds blow from many directions -Blowouts are sandy depressions in a sand dune ecosystem caused by the removal of sediments by wind. -Not all dune areas are deserts= dune topography stabilized by grass

solution load

-SOLUTION (DISSOLVED) LOAD is the material carried in chemical solution. With a concentration of 0.1% the Mississippi River transports 120,520,000 tons/yr of dissolved load into the Gulf of Mexico each year.

Suspended load (silt)

-SUSPENSION LOAD - SILT SIZE GRAINS

suspension load

-SUSPENSION LOAD is the fine sand, silt, and clay size particles that are carried in the water. The Mississippi River carries 406,250,000 tons/yr into the Gulf of Mexico as suspended load. -CAPACITY is a measure of the total amount of SUSPENDED LOAD that a river can carry

Lee/cascade face

-Sand dunes form as sand saltates up the windward slope and cascades down the lee (downwind) face to form the cross beds typical of sand dune deposits in sedimentary rocks.

Pipe vs difuse flow

-Sandstone - diffuse flow among grains -Limestone - pipe flow through fractures

Sonoran and Mojave deserts

-Southwest U.S.

Trellis drainage

-TRELLIS (RECTANGULAR) DRAINAGE is typical of regions where variations in bedrock erosion resistance controls drainage. For example the Valley and Ridge topography of the Appalachian Mts.

Corps of Engineers

-The "modern" Mississippi River is intensively managed by the U.S. Army Corps of Engineers. -In 1954The US Army Corps Of Engineers cut a 4 mile wide channel between the Mississippi River and the Atchafalaya River -After the disastrous floods of the 1920's and 30's, Congress authorized funds to study and control the Mississippi River and its tributaries. At that time, the Army Corps of Engineers was the only agency capable of the project, and they are still in charge of the program.

Ganges Delta

-The Ganges Delta is the type Tide Dominated delta. The country of Bangladesh is entirely on the Ganges Delta.

Longitudinal profile

-The LONGITUDINAL (long) profile of a river approximates a parabola when the stream is GRADED The slope is steeper toward the head and gentle at the mouth. Rivers erode down more rapidly at their head. -gradient and base level -Rivers flow faster at their head (origin) and slower at their mouth (end) -Rivers erode down more rapidly at their head. -a nickpoint is an abrupt change in the longitudinal profile of a stream.

Mackenzie River

-The Mackenzie River of Canada is the second largest river in N. America. The Mackenzie drains north into the Arctic and played little role in the settlement of North America. -The Mackenzie River system is the second largest drainage basin in north america

Lake Itasca source

-The Mississippi River originates in LAKE ITASCA, MINNESOTA and flows north to Lake Bemidji before turning south. -SOURCE OF THE MISSISSIPPI

Pliocene Mississippi River

-The Pliocene Mississippi River (PMR) drainage basin extended from Hudson Bay to Louisiana and was up to 200 km wide at the latitude of Tennessee. -The age of Upland Complex gravel and sand deposited by the PMR was determined using cosmogenic isotopes

Artificial cutoff

-The U.S. Army Corps of engineers wrestled the mighty Mississippi into submission using this -shorten the length of a river. The Mississippi distance from Cairo, Illinois to New Orleans, Louisiana was shortened 152 miles by 16 artificial cutoffs, all downstream from Memphis. Shortening increases the gradient thus speeding up the river water and preventing the buildup of a flood crest. The artificial cutoff program now seems complete as a proposal to shorten the river at New Madrid Bend (Missouri) was rejected.

Upland Complex

-The UPLAND COMPLEX is a terrace gravel formed by the Pliocene ancestor of the modern Mississippi River (PMR). The Upland Complex underlies the loess on the Chickasaw Bluffs and Crowley's Ridge and is an important source of construction gravel and sand. -is a gravel and coarse sand that disconformably underlies the loess and disconformably overlies Eocene formations on the Chickasaw Bluffs and Crowley's Ridge. -PLIOCENE MISSISSIPPI River deposited the Upland Complex about 3.2 million years ago

Down cutting

-The bottom of the Wolf River is down cutting upstream causing scour around bridge abutments.

Herodotus

-The term delta was coined by Herodotus, circa 250 BC, for the delta of the Nile River when he was shown maps of Egypt by his Egyptian hosts. He correctly noted that it "is the gift of the Nile".

Nile Delta

-The term delta was coined by Herodotus, circa 250 BC, for the delta of the Nile River when he was shown maps of Egypt by his Egyptian hosts. He correctly noted that it "is the gift of the Nile".

Zone of aeration

-The zone of aeration is the region between the earth's surface and the water table. The main components of this region are the soil and rocks. Their pores are at times partly filled with water and air, and aeration occurs when the air and water mix or come into close contact. -The presence of water and oxygen gives rise to the formation of soil moisture, which influences the rate of corrosion when it comes into contact with metallic objects buried in the ground. -The zone of aeration is also known as the unsaturated area

Zone of saturation

-The zone of saturation is the ground immediately below the water table. The pores and fractures in soil and rocks are saturated with water. -The zone of saturation is less corrosive than the unsaturated zone above the water table. The moisture content in the region is at one extreme while the other extreme is in the dry soil.

Transverse dune

-Transverse dunes have their long axis perpendicular to wind direction. -Diaz, Arkansas

river velocity

-VELOCITY, the speed of the current, is a measure of river energy, the faster the water the more the energy. -Velocity is controlled by 3 factors, gradient, roughness and load -Velocity is a measure of a streams energy - faster flow = more energy -Velocity is controlled by 3 factors gradient - slope of water surface roughness - bottom irregularity load - sediment carried -doubling velocity increases capacity by 32 times .

Roughness of channel

-Velocity is controlled by 3 factors, gradient, ROUGHNESS and load -roughness - bottom irregularity -A rough bottom increases the frictional drag between the water in the river and the bottom. For example, in rivers used to float logs to a sawmill it is common for the bottom to be littered with water logged debris thereby materially slowing the water velocity. A local example of a stream choked by trees is the Wolf River.

Waterfalls

-WATERFALLS INDICATE A NICKPOINT Yellowstone Falls flows over a lava bed in an easily eroded volcanic ash sequence. -Niagara Falls is actually 2 falls; the American Falls and the Horseshoe (aka Canadian) Falls -ANGEL FALLS, VENEZUELA: The world's highest waterfall, and one of the most beautiful, plunges more than 3,200 feet down a sheer cliff deep

Point bar

-a floodplain feature -A POINT BAR is the sand deposit formed on the inside of a meander bend. -At the same time the cut bank is eroding the opposite side of the rive will form a sand deposit called a POINT BAR.

Hydrograph

-a graph which shows the the discharge of a river, related to rainfall, over a period of time

Rip rap

-a protective coating of rubble laid down at erosion-prone stretches of a river. They protect harbors and other important facilities from undercutting and bank caving. -Rip Rap prevents erosion and reduce the load of the river and thereby speeding up the water.

Revetment

-are a protective coating of concrete laid down at erosion-prone stretches of a river. They protect harbors and other important facilities from undercutting and bank caving. -Revetments prevent erosion and reduce the load of the river and thereby speeding up the water. -Revetment - masonry protection of river bank

Drainage divide

-are the high areas that separate adjacent drainage basins.

Old River Floodway

-divert it into the Atchafalaya River or Lake Ponchitrain.

Missouri River

-flood in 1993 -The Missouri River flood of 1993 set records along 1600 km of the Missouri and Mississippi Rivers ($19 billion damage). FEMA initiated buyouts of 7700 properties ($56 million) of flooded land. Unfortunately these were offset by aggressive floodplain development in the St. Louis area; 28,000 new homes, 23% population increase, 26.8 sq km, on land flooded in 1993.

Entrenched meanders

-form when meandering rivers are REJUVENATED by regional uplift

Gradient

-gradient = slope of water surface -is the slope of the surface of the water. Gradient can be measured as the angle of slope or the feet of fall per mile of length of a river.

Discharge

-is a measure of the volume of water transported by a river. It is a simple function of the velocity of the water times the cross section area of the stream.

Mars dunes

-is the ONLY OTHER PLANET that has wind-created features -Dune fields and dust storms indicate wind activity is presently ongoing. -Martian dunes are comparable in size to the largest on Earth.

Cut bank

-is the steep slope formed where the river erodes into its floodplain on the outside of a meander bend. -At Fulton, Tennessee the Mississippi River has cut into its east bank. In the past 50 years it has undercut the Chickasaw Bluff, eroding away the front yard of a house and undercutting a house. This phot was taken in 2000, the house may be gone by now

Base level

-is the surface towards which a stream erodes down, i.e. down cuts. Base level is sea level for large rivers but may be a local elevation such as a lake for rivers that do not reach the sea.

Mississippi Delta

-is the type river dominated delta

Deranged drainage

-is typical of young recently deglaciated drainage of the northeast US and most of Canada.

Florida

-karst landscape -central florida= riddled with sinkholes!!! (most common in warm, humid climates)

Indiana

-karst landscape -sinkholes

Central Tennessee

-lots of sinkholes -karst landscape

Thalweg

-meandering stream profile: -The THALWEG is the line of fastest flow along a river's course. -The THALWEG is the line of fastest flow along a river's course. The thalweg erodes into the outside of meander bends and deposits on the inside of bends, thus causing meanders to migrate downstream over time.

Niagara Falls

-nickpoint!! -Niagara Falls is actually 2 falls; the American Falls and the Horseshoe (aka Canadian) Falls

Disappearing drainage

-occurs where creeks abruptly vanish down into the subsurface. Disappearing drainage is common feature of karst topography. -northern Black Hills, SD....here Boulder Creek disappears into its stream bed.

Karst topography

-regions of LIMESTONE BEDROCK where topography is dominated by SINKHOLES -found worldwide but Karst is common in Central Tennessee, Kentucky, Indiana, Missouri, Texas, Florida. -Karst topography is common on the Highland Rim, Central Basin, Cumberland Plateau and much of east of Tennessee. -tower karst

Sediment input

-sediment accumulation in the channel while slowing water flow and trapping sediment near the riverbanks -???

Pseudokarst

-similar in form or appearance to limestone karst features, but is created by different mechanisms. Examples include lava caves (e.g., Hawaii) and loess caves along the Chickasaw Bluffs -Pseudokarst in the Peoria Loess in Meeman -Shelby Forest State Park creates depressions when ground water undermines the surface.

Braided river

-simultaneously occupy several channels in the same valley. -They are typical of high gradient plains near glaciers and mountain fronts.

Straight river

-straight - typical of mountain rivers -BLACK CANYON OF THE GUNNISON RIVER National Park

artificial levee

-straighten, raise and fill-in the natural levee system.

Meander cutoff

???

Tide energy

???

Triangular delta class

???

Wave energy

???

Channel cross section

????

Impoundments

????

Cave, Cavern

CAVES: form in the PHREATIC ZONE (Zone of saturation) when acid ground water percolates through fractures and along bedding planes (pipe flow) in LIMESTONE, dissolving and enlarging the fractures. -A CAVERN IS A LARGE CAVE. Caves form where limestone bedrock is dissolved in the vadose (saturated zone).

Stalactite

STALACTITES hang from ceilings Stalactites the tites go down -Stalactites commonly grow where water seeps through concrete walkway ceilings as in this illustration from the north side of the English building of the University of Memphis. -man made

Stalagmite

STALAGMITES grow from the floor Stalagmites the mites go up. -stand on cave floors

Blanchard Springs, AR

Stalagmites stand on cave floors Cave features - ceiling breakdown BLANCHARD SPRINGS CAVERN

Dendritic drainage

The tree-like drainage pattern created if rivers cross a gradual slope over one basic type of rock.

Water table

The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water.

flash flood

a rapid flooding of geomorphic low-lying areas: washes, rivers, dry lakes and basins

downstream flood

occurs in a larger, lower part of a drainage basin

natural levee

raised river bank that results when a river deposits its load at the river's edge

Blue holes

they are SINKHOLES AT SEA -form when karst topography formed when sea level was lower than it is now and later flooded when sea level rose. -form sudden drops in underwater elevation and get their name from the dark and foreboding blue tone they exhibit when viewed from above. -can be hundreds of feet deep. -largely devoid of oxygen that would support sea life due to poor water circulation - leaving them eerily empty.  -Some blue holes contain ancient fossil remains preserved in their depths. -ex:The Great Blue Hole in ambergris cay, belize