7. Sedimentary Environments 2

 Aeolian processes and landforms

Erg Chebbi, Morocc Morocc o  pixdaus.com/pics/cyu2na7zGGmZb4PVI5.jpg 

 Aeolian processes

 Aeo l ian p r o c es ess s es  Æolus (Greek god), keeper of the winds

Wind transport ,

,

,

64.19.142.11/n-e-r-v-o-u-s.com/education/simulation/images/reptation.PNG

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian transport 

Dust/sand storms aeolian turbidit y currents

arise when a gust front or other strong w ind blow s loose sand and dust from a dry surface Red Sea

 Al A sad , Iraq

en.wikipedia.org/wiki/File:Sandstorm.jpg 

en.wikipedia.org/wiki/File:Redsea_sandstorm_May13-2005.jpg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian transport 

Dust devils a strong, well-formed, and relatively long-lived whirlw ind thought t o be related to very int ense local heating of the air that results i n instabilit ies of the air mass

Mars

en.wikipedia.org/wiki/File:Marsdustdevil2.gif 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian processes

Sailing/sliding r ocks mystery a geological phenomenon where rocks move in l ong tracks along a smooth valley floor w ithout human or animal intervention recorded and st udied in a num ber of places around Racetrack Playa, Death Valley, where the number and length of t ravel groov es are notable

en.wikipedia.org/wiki/File:Racetrack_Playa_%28Pirate_Scott%2  9.jpg  en.wikipedia.org/wiki/File:Death_8_bg_082303.jpg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian environments

Desert Latin d ēsertum, ‘an abandoned place’  landscape or region that receives an extremely low amount of precipitation (< 400 mm/yr), less than enough to su pport grow th of mo st plants  Ant arc ti c Deser t, An tar ct ic a area: 13,829,430 km 2

en.wikipedia.org/wiki/File:AntarcticaDomeCSnow.jpg 

N. Ramos | Geology 11 Principles of Geology

Sahara Desert, Afri ca area: 9,100,000+ km 2

en.wikipedia.org/wiki/File:Libya_4985_Tadrart_Acacus_Luca_G aluzzi_2007.jpg 

Lecture Notes: Sedimentary Environments

 Aeolian environments

The worl d’s deserts

at least 12 consecutive months without rainfall  less than 250 mm of annual rainfall  mean annual precipitation of 250 to 500 mm 

Thomas (1989) in Huggett (2011)

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

Erosional aeolian features

Ventifacts rocks that have been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice cryst als

64.19.142.10/upload.wikimedia.org/wikipedia/commons/a/a4/Ve ntifact_at_Ventifact_Ridge_in_Death_Valley.jpg 

N. Ramos | Geology 11 Principles of Geology

64.19.142.11/upload.wikimedia.org/wikipedia/commons/thumb/  e/ea/Mendenhall_1905_USGS.jpg/800pxMendenhall_1905_USGS.jpg 

Lecture Notes: Sedimentary Environments

Erosional aeolian features

Desert pavement / reg a sheet-like surface of r ock fragments that remains after wind and water have removed th e fine particl es covered with closely packed, interlocki ng angular or rounded rock fragments of pebble and cobble si ze  Ahag gar Moun tai ns , Alg eri a

Mojave Desert, USA (CA)

64.19.142.10/upload.wikimedia.org/wikipedia/commons/thumb/  1/1d/Hoggar13.jpg/800px-Hoggar13.jpg 

64.19.142.13/upload.wikimedia.org/wikipedia/commons/thumb/  9/90/DesertPavementMojave2010.JPG/800pxDesertPavementMojave2010.JPG

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

Erosional aeolian landforms

Yardang Turkic: ‘steep bank’  a streamlined hill carved from bedrock or any con solidated or semiconsolidated material that resembles the hull of a boat form in environments where water is scarce and the prevailing winds are strong, uni -directional, and carry an abrasive sediment load Dasht-e Lut desert, Iran

3.bp.blogspot.com/Nkpij5Vr_pw/TZLhb822LaI/AAAAAAAAAFA/vXQk8sgG6xg/s16  00/yardang_large.jpg 

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www.sciencephoto.com/image/173635/530wm/E4600528Yardang_field,_Dasht-e_Lut_desert,_Iran-SPL.jpg  Lecture Notes: Sedimentary Environments

Erosional aeolian landforms

Modified yardang The Great Sphin x of Giza, Egypt

64.19.142.12/upload.wikimedia.org/wikipedia/commons/thumb/f/f6/Great_Sphinx_of_Giza_-_20080716a.jpg/800pxGreat_Sphinx_of_Giza_-_20080716a.jpg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian processes

 Aeo lian processes  Æolus (Greek god), keeper of the winds

Wind deposition Sedimentation grains fall out of the air or stop creeping forward  Ac cr eti on grains being moved by saltation hit the surface with such force that some grains carry on moving forward as surface creep, but the majority come o res w ere ey s r e Encroachment takes place on a rough surfaces, wherein grains moving as surface creep are held up while saltating grains may move on N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian depositional landforms

Sand s heets and r ippl es flat, gently undul ating plots o f sand surfaced by grains that may be too large for saltation wind blow ing on a sand surface ripples the surface into crests and

Selima sand sheet, Egypt and Sudan area: 60,000 km 2

www.egyptoffroad.com/PhotoGallery/gilftrip/untitled36.jpg 

www.bcarchaeology.com/Images/The-Selima-Sand-Sheet.jpg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian depositional landforms

Dunes a hill of sand formed by in teraction w ith the wind ; may be sub-aqueous, lithif ied, or coastal large dune fields are known as ergs Issaouane Erg, Algeria

Slip face

en.wikipedia.org/wiki/File:IssaouaneErg_Algeria_ISS010-E13539.jpg  en.wikipedia.org/wiki/File:Dune_en.svg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian depositional landforms

Dunes a hill of sand formed by in teraction w ith the wind ; may be sub-aqueous, lithif ied, or coastal large dune fields are known as ergs Cerro Blanco, Peru height: 1176 m

Badain Jaran Dunes, China height: 500 m

www.travelgrove.com/blog/wp-content/uploads/cerro-blanco.jpg    www.linternaute.com/nature-animaux/geologie/photo/les-dunesdu-monde/image/badain-jaran-mongolie-455373.jpg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian depositional landforms

Dune shapes

www.uwgb.edu/dutchs/Graphics-Geol/geomorph/dunetype.gif 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

crescent/barchan Great Sand Sea, Egypt

parabolic Greenwi ch Dunes, Canada

 photography.nationalgeographic.com/photography/enlarge/barc  han-dunes-photography.html 

transverse Mojave Desert, USA (CA)

64.19.142.10/niche-canada.org/files/images/parabolic-dunegreenwich.jpg 

longitudinal/seif  Rub' al Khali, Saudi Arabia

www.nasm.si.edu/ceps/research/mojave/5-95.jpg 

en.wikipedia.org/wiki/File:Rub%27_al_Khali_%28Arabian_Empt  y_Quarter%29_sand_dunes_imaged_by_Terra_%28EOS_AM1%29.jpg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments

 Aeolian depositional landforms

Dune shapes

linear

star ,

  ,

www.flickr.com/photos/davec71/42940367/sizes/o/in/photostre am/  www.nasm.si.edu/ceps/research/earth/craddock_simpson3.jpg 

N. Ramos | Geology 11 Principles of Geology

Lecture Notes: Sedimentary Environments