143 lines
5.2 KiB
Plaintext
143 lines
5.2 KiB
Plaintext
lb ge wrong in desen, and us pur whole pepulariens al
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risk; waier ln pariieuiar musl be subleei ia lreuueni
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analysis lor ppllulidn and 5am. and deep bare All well
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walers rlganiusly lesled lor excessive mineral and
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radieaeuve pellulanls,
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11.5
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LANDSCAPE FEATURES IN DESERTS
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Oeeupled and impmnlged and lands premu a lelal
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mosaic DI vegeianerr, wlln very dilleiem changes
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bbvious iu lhe iraveller. 1p lud" aueh a landscape
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mean. a dsigner needs Io MK,
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- l-mcss- wheiher wind, waler. er ml-lllrariun rs
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aeuve Locally
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~ ROCK AND soil. mm. lnese deerde leeal
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.espunse la prueess and pruduee eharaeierirlie
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landlenns.
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- ASPECT. even slighi shading by hills ehanges
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uppimunlries and piumplrs gnwlh
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. FIRE FREQU£NCY, and ihe nine sinee lhe lasl lire.
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- THE DATE or THE LAST HEAVY RAIN lmum
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ihan I2 innil whieh may have been lhe lugger ler a
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spedlie 51st ml plane (mmilmzm ol speeiesl.
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ln drylandr. eresipn landlorms are balli rniire
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signilieani, umsplcmus, and more nurnenius in rype
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lhan in humid areas, Exrensive deserls may show
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ranges or MOUNTAINS wuh (umple’x hug valleys and
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sheavsldzd gnrgvs draining mse. lselared m grouped
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gramne domes lleELbERcsl rise sleeply bui pl lhe
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deseri plain, and lhe eumplex scAlP AND
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PEDIMENTIindsupt-s nl laulees, Infill and wadis
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lbdi clnyuns) are alsu lealures el lhe deserl
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EADLANDS ul eomplea, eroded, seller sedimenls may
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devekvp an unrunselidaled art», and sharp—sided and
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mush blanched cuLcHrs lgulliesl develop on sleep
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slopes Series 0! lulds give a BASIN AND RANGE
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rppdgiaphy ever most desen borders near mounlains,
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and are a leaniie 01m! areal basin desens ul Nunn
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Amensa
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True desers has lhe blond primary landseape
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pavemeni elassiliealion nl ERG lsandy deserll,
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HAMADA (lurk and boulder pavernenll, and m
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lgravel iurlaeesl. oi iliese, erg is lurrher broken down
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imn dune rypes and lurrnanuns, some elwhieh may lie
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over the reg a! harnada base lieg u generally ralren us
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he an area hum which sand and sill has bull removed
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Eng is eumposed pl SANDPLMN as near—level sand
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sneeis river various supsrrales lalsu eallrd sand heldsl
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and dunes pl several types
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in rural, deseri landseapes are angular, and aenvely
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eroding Humid unis. and tspeually lhase darned
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wilh grasslands and lemsls, have seller and more
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runnded uullines, Nlm rare rilll laees al receni
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laulkhnes nrshurellneslr- die my
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lhe lewer slepes, basins, and playas lpansl a!
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overgrared and eluded drylands need anenliun, as do
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rhe dry river beds and iqulkn inal lie btlow lhe
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316
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surlaee sediments rur ihis mm and haul: a vu'y
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seaireied lirerarure exlsls on deseri siraiegies wiih
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respeei m speeilie landlprm lypes, l have med io
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assemble here a rel olsrralegles suned ns speellie sires
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and landlmlu lrlgure my.
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schPs AND WADE
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Wherever pedpds ol upr ,pr searps of laulls lraeiure
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dseri peneplalna, lung rhll-unes lsduie nmnmg many
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lens bl liilemeriesl srand abeve lhe lower erusldn
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surlaee. While lhese uplili scarps are also visible in
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humid lands, in desens lhey remain less mud, and
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develop eharaclerirrie prullles. These pmliles, angular
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and esseulially simple, wi|l qluckly emerge liens. lne
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reunded hills bl laulied hunud areas enee lhe
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vegemien iselmred and duem’mahnll selsln,as il h”
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emerged in cuunny eleaied el lrees and ended in lhe
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1920's in Sanlh Ausualia
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The prueess develops as per ' use in ln lnie
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dsens, lhe prplile is rypieally :5 per Figure “.5 (sear-p
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seeder. above and men plan below) Usually, lhe real-p
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laee is lairly siraignl or enly genlly eurved, and lhe
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wadis are an near righr-angles in are scary Lire Mlhin
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ihe wadl side, valleys leave again al near nthngles
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iu ihe main valley; lhe pauern u lhai 0! parallel laull
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wm and eumpensaung yeinls in ihe reek,
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Cumplea bux eanyans lwadb ending in dim), mesas
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lisblaied mm of lhe main searpl, and bunes (0‘le
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searp seeiuuisl make varibus scirpellnes, Searps are
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rapped llhe upper erdsinn surlaeei w' h durable
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lmnslones, hard sandslpnes bands, lernerele, pr sllvaere
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crustal malenal clills and searp laws are generally 0!
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seller, samwmcs bauiuie ialumium paidel maierlal.
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and lhe lower enisum surlaee ia euvered wl|h sills and
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sands washed em 0! ilie wadis and laier dislnbuied by
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winds
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When u rains, lhe hard lock suilaee ol lhe upper
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searp surlaee sheds inusi ul lhe waler, which lollnws
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genlle valleys behind lhe srarp and lallr as sudden
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waleilalls 0v" lhe clill ends el lhe wadis lusi belpre u
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dees so, however, lurbulenee may sedur mu deep holes
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in (M upper suflam irigure ml Warer may rush in
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iurienis lhrerugh lhe sysiem lbr 34 days aller rain. and
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llie volume diseharged largely depends on lhe
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ealehrneni area
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A tflflaln nl waver, or nlls, may lall alemg lhe whole
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scalp lihere is usually a dbwrulupe iusl peluie lhe chm
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bu| rnis is a mueh mole ephemeral linw. Nevenheless,
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ever lime, lhls euriain pl waier or (Illlrbase seepage
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may panlv undemu! lhe soll sear-p, and rlguie 11.5
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shuws ene pl ruse searpliase eaves in lhe plume.
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leq lhe rllll "sell. lhe nu|ch ai lhe base (in be very
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large liall enough In rule a Emmy house) or very
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small lnisl large enough |u e shade to a kangaroo m
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a sheep) Norrlies in lhe clill lnee may be peeupied by
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plgl'cus, ewls, swalldws and swuis, rpdenls, repules.
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and M or lheir larval lenns. shade, like waier. is a
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eniieal mu: m lhe deserl
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The wadi pienle, m lair ippmximanun bl il, b Ibo
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