Show r to TT i AM DOMES hi s dunt OP hair remarkable sand dunes of the T peruvian dbert have attracted he of every visitor to tills arid creglon ri glon the striking feature of thena formations fornin tiong Is that they hoy slowly but shift their position in the lie saine direction in the ho geographical geographic ill journal of london W 9 barclay thus describes dem eribes nod and explains q these traveling blind julles lui although tile ho of tile the dunes lire are to bo be found in III the lie western ligia of the pampa the weathering r of the conglomerate bed fro from m blitch 11 h 1 c alile they take their origin Is n no 0 tic e i elsewhere along the Per e coast 0 fist one of my illy most avid vivid peruvian reco recollections uvIon lq on of 1110 ho steamer voyage along ill he desolate coast front from lanin to mol lot leodo Is a vision the party I 1 1110 sun of it a great llaine flame colored hill that seen through the coast fogs presented almost tile appearance of a elty ltv on oil fire anre tills flonie effect was ns As I 1 afterwards ascertained due to blind 1 abul I dust blowing across its upper tipper ridges from mollendo Mol lendo the winds its wily up the he deeply eroded flunks flanks of tile the const coast hills the hot air rising front froni the desert keeps back or dissolves lie ito which flitch attempt to lunke their way ny across the andean crests cresta to tile tho son sen find and rijn Is reckoned to kill fall on oil tills this coast not more diore than oneo once in fit seven years when tills this occurs however low its erosive effect on oil the soft loose looie soil froll Is striking watercourses Water courses 15 1 5 to 20 feet deep fire cut in A few hours one of these rare phenomena had place it few days before my illy visit it does not pay the railway when han constructing ting its trade track to allow openings for these infrequent cloudbursts and ono sees seea in consequence cal solid earth banks built florig ill alio llio hill flanks damming of grout great depth extending sOme sometimes a mile ur or more inore on oil the upside I 1 elrd that forms forma the dunes on ren reaching ching tin tile pacific fringe of the pampa or desert dei ort del sacramento titter after fin an ascent front from the const of some feet one begins begin to feel fed the wind ind which Is responsible for the lie formation to the lie prevailing winds on oil tho lilt western border of the lie desert tile alp solid remains largely inchoate but after about 15 16 or 20 miles duries dunes begin begill to mill find these Inc renso in number her till on nearing the inland fringe I 1 sonic soine 25 nilles miles from arequipa they can be observed in ili serried battalions accompanying compa nying the rall railway way once formed for ined the dunes take their heir typical halfmoon half moon shape and proceed in III stately sequence southeast neross tile the pallina until they reach come large obstacle or abrupt change of level it the barrier Is negotiable they ey adopt themselves to cross cros it the durie dune projecting itself into the easiest passes and up to tile limit of its ita sand mass ions s once tho obstacle obit acle Is crossed the lie vanguard of the lie dune done marks time until tile rear catchen UP fornis foisia once moro into it halfmoon half moon shape and proceeds on oil its way these duties often ofte n attain it 11 considerable size the march of tho the dunes Is assisted by the lie sand ripples whose more exposed surfaces tire aro blown blon onward by iho whid ind the solid band climbs clinies the steep back of tile duno dune more slowly than tile the low salient wings hence the halfmoon shape small particles travel tit at relatively high speed benr ground level as far its as the projecting project ing points or horns but its is soon ns as they reach thein libin they tire aro on the lee of the wind and their farther progress Is checked until til the mass of the dune drine patches catches up ill thus thu g the di distance tho the sand travels along tile he points la Is dependent on the maximum height of tho the back of the dune and tills in turn depends op the force of wind move yards a year owing to my illy short stay in the pampa I 1 was not able to check tile alie dunes rate of more march by personal person nl observation but I 1 was informed ly by plate layers labels and other ballway men whose duties dulles necessitate watching them thein that tile rate late Is about yards per wiluin the high hills flanking tile the desert near arequipa tire lire too steep to kllc dunes to proceed farther they therefore pile up till in it a sort of it sandy cemetery fit at the eastern edge of the pain iam Z 1 1 1 I 1 eo i ear 4 OVID DUNE dunc IN desert of tile dunes the clio general direction of tills wind Is front froni tile northwest being caused by radiation front from tle the altiert surface awl lio file consequent const in ili ru ruh h of cooler lir front from tile Vil it t lit fit about 20 fill miles 1 es till nit hour on oil tile the flat between I 1 like ho ridges the hed of tills desert Is elt lefly formed of the following followill constituents ili hn order of their lin lilt IRr tance quartzite Kyp gyp ill if orllo mth tron iron tind crystals ry and quartz qin irtz the whole la Is packed and b ended ly by lio lie aji penni which hit alnis run into and filled dinatle perpendicularly thus weathering tin the Is found lit ili IA lids ds llo in ili the lie of it arequipa and Is cut clit into blocks for building purposes purpose they ring when struck Klc ilko will well bri bricks clis tho quartzite borins tho main muss of it the hills surrounding tile lies dex ert it weathers into a brick red oxide on oil like lie slit face holcli gives the desert kg its toile one milking making it lie slaty whito foai linns noticeable by contrast tile quartz ts is la Is in ili tiersie ased in ili tile conglomerate but bat in forin showing nn fin signs of wn wit ter wearing it must therefore bo be attributed tri buted to vol canle the go nests of tile nicil enild dunes Is best sew seen on the pacific or western fringe of tile he d esert desert chero tho winds tire eating awny away tile ridges possibly the rvin altis int t on an ancient higher level ii litch run out from froin the lie i tte ite hills in hi A adli tit at right VII pu pit before they reach the end elid jina however and nc ALI tile hilly hills deflect ill the nir air ili different directions duties occasionally advance over or threaten lie roll wity ny line tile the method of avoiding the lie f threatened obstruction Is hut effective A couple of men go out with long bundled spades i find a wheel har row and collect loose pebbles grit front the surface of tile tho this proceed to scatter eci itter in ili it n thin inar over om r the liick inick of the unfortunate dune tito pebbles arrest irr ct tle tile action of tin the ripples 3 and so fco interfere with the even circulation jf df the 8 and particles which Is appo lyew ly na Is esse to progress of lite lio dune d II 11 ili us its the of blood to it bunion being very shortly the duno dune us 11 lops idad i leipe stig gIng where tho debris has licen east upon it ind and offering 11 melt rounded buck backa it breach to tile nellon of the wind ft ind the progress of nt gration Bint lon Is fairly rapid and tit nt tile caid oil nothing Is 14 left on the except tho lie original wheelbarrow londs foods of grit and pebbles which illicit to exercise the the dunes lines advance over pebbles and stouts without lt lout disturbing their tion I 1 noticed behind several large dunes se a that lint obviously loft lind not si lifted from broin their bod bed just us its pil pebbles eq fully lie secure on the lie seashore in ili ho file swell of tho the breakers generally speaking tho the smoother tho ce of tile pampa and tile lie higher the wind tile lio forger and more perfect be becomes collios tin the |