© 2007, John Wiley and Sons, Inc. Physical Geography by Alan Arbogast Chapter 18 Arid Landscapes and Eolian Processes Lawrence McGlinn Department of Geography State University of New York - New Paltz

© 2007, John Wiley and Sons, Inc. Arid Landscapes & Eolian Processes Arid Landscapes Eolian Erosion & Transportation Eolian Deposition & Landforms Human Interactions with Eolian Processes

© 2007, John Wiley and Sons, Inc.

Arid Landscapes 3 factors influence arid climates: Subtropical high pressure Rainshadow Distance from large bodies of water

© 2007, John Wiley and Sons, Inc. Desert Geomorphology Water important to landforms in arid regions – little vegetation to slow intermittent erosion Arroyo – steep-sided gully cut into alluvium In undisturbed, horiz. rock layers more resistant sandstone or limestone forms flat caprock above easily eroded shale Result is landforms flat on top w/steep sides: -Plateau-Canyon -Butte-Mesa -Pinnacle-Playa

© 2007, John Wiley and Sons, Inc. Arroyo

Desert Landforms Note: Tops of most landforms once part of same surface, since partially eroded away

© 2007, John Wiley and Sons, Inc. Playa

Eolian Erosion and Transport Wind-based processes important in deserts b/c: Strong winds common in desert Large supply of sand & silt to be blown Vegetation minimal – wind free to erode

© 2007, John Wiley and Sons, Inc. Fluid Behavior of Wind Wind acts like a fluid, like water, but less dense Faster wind can move larger particles Threshold Velocity for wind to carry different sized particles

© 2007, John Wiley and Sons, Inc. Particle Transport Silts and Clays carried in suspension Sand bounces along – saltation, or Sand rolls slowly along – creep

© 2007, John Wiley and Sons, Inc. Eolian Erosional Landforms 2 types of wind erosion: Deflation – wind blows loose soil away: leaves coarser pebbles & cobbles, called Desert Pavement when deflation causes basin to form, called Deflation Hollow

© 2007, John Wiley and Sons, Inc. Eolian Erosional Landforms Abrasion – wind blows sand along a surface to polish & abrade it Ventifacts – rocks shaped by abrasion: pitted, grooved, polished Yardangs – elongated, wind-sculpted ridges caused by abrasion

© 2007, John Wiley and Sons, Inc. Eolian Erosional Landforms Deflation/Desert Pavement

© 2007, John Wiley and Sons, Inc. Eolian Erosional Landforms Abrasion VentifactsYardangs

© 2007, John Wiley and Sons, Inc. Eolian Dust Storm