Mojave desert, USA - desert landforms

Where is the mojave desert located?

south west of the USA

occupies parts of the states of california, nevada utah and arizona.

how large is the desert?

covers an area of 124000km squared

What is the physical geography of the mojave desert?

• typical mountain based topography with sparse vegitation

• highest elevations are over 3000m

• lowest points is death valley 86m below sea level (lowest elevation in north america)

What is the climate of the mojave desert like?

• annual rainfall of less than 140mm as north america’s driest desert

• summer temps reach 50ºC

• winter temps can plummet to -7ºC

• rain tends to fall in thunderstorms in summer

• affected by strong winds

what are the river systems in the mojave?

small number of exogenous rivers that flow through including colorado river in the east

What is the level of settlement in the mojave?

• sparsely populated, although there are a few cities such as las vegas which has a population of nearly 2 million

what desert landforms are present in the mojave national preserve?

• alluvial fans - lucy gray alluvial fan

• pediments and inselbergs - cima dome

• playa - soda lake

• sand dunes - kelso dunes (dunmont dunes located outside the preserve)

What is the mojave national preserve?

protected area in the south of the desert in southern california

famous for landscapes and desert landforms which it has many of

what is the lucy gray fan?

alluvial fan

• in the north of the preserve radiating out from a canyon through the lucy gray mountains

• drains into the Ivanpah valley

• below the mouth of that canyon multiple channels separate off as channels become chocked with sediment

• courser material remains at the top of the fan whereas finer materials migrate further down the slope

• water only reaches the ivanpah playa pond in intense storms

what is the cima dome?

pediments and inselbergs

• erosion and weathering have stripped away mountainous landscape to leave behind extensive rocky pediment

• this leaves behind isolated rounded granite inselbergs

What is the soda lake?

playa

• playas common in the Mojave - soda lake is the largest

• many exist due to where lakes and marshes formed in the last glacial period, which dried up around 8000 years ago today only hold water after flash floods

• located in the west of the preserve

• extends over an area of 150km squared

• during summer salt crusts develop in places on the lake and in late summer these salts ar4e moved by winds creating haziness in the air across the region

what are the Kelso dunes?

sand dunes

• wind plays an important role in their development

• Kelso dunes and neighbouring devils playground form an extensive area of sand deposition on the west of the preserve

• Kelso dunes extend 120km squared and the largest dunes in the desert

• mixture of mobilised and stabilised (due to vegetation) dunes

• tallest is 200m above the floor

• most of the sand originates from the San Bernardino mountains granites

how do prevailing winds affect the ridge profile of the Dumont dunes?

• located in the north of the desert at top of death valley

• prevailing winds from south carry sand grains up windward side of the dune, blowing over and become deposited as grainfall.

• the angle on the other side builds to reach natural angle of repose (maximum angle before slope collapses) resulting in grain flow

• windward side is more stable as it is compacted by the forces of the wind with a consistent angle of 20 degrees