Deserts

1. Deserts BY STURDIPANTS

2. Geology in Arid Climates • Unlike the smoothed hills and rocks of humid regions, arid climates contain angular rocks and steep canyon walls • This is because mechanical weathering dominates in deserts

3. Water in Arid Regions • There is rain in deserts, so chemical weathering does occur, although only in bursts • Desert streams typically only flow after rains. We call these ephemeral streams

4. Basin and Range Systems • Unlike most other streams, desert streams don’t always reach oceans • These systems in which water temporarily exists in bowls (basins) between mountains (ranges), are called Basin and Range systems

5. Playa Lakes • Deserts lose water quickly due to both evaporation and infiltration • However, after heavy rainfall, temporary lakes called playa lakes may exist • Although lakes and streams are short-lived, water is still the #1 erosive force, before wind

6. Wind Erosion • Strong winds can pick up small particles, transport them, and deposit them elsewhere • Deflation – lifting of loose, fine-grained particles • After deflation occurs, only large sediment is left behind, called – desert pavement

7. Wind Deposition • Exactly the same as water, when wind loses velocity, it no longer has the ability to transport sediment • This especially happens as the wind reaches some obstruction • This deposition of wind blown sediment creates formations like sand dunes