ON THE PACIFIC COAST 333 



once blown over the cliff is sheltered by it from the further action 

 of the wind. 



Piura lies nearly east from Payta, at a distance of 14 leagues, 

 during the first seven of which the tablazo rises gently and 

 equably, and the road is stony, or in some places dusty, but 

 nowhere sandy. At midway, which is also the highest point of 

 the route, there is a tambo or hospitium, where a supply is kept 

 of water and food for man and beast, chiefly brought from the 

 Chira with great trouble and expense. There the traveller, 

 having started from Payta about sundown, reposes during the 

 midnight hours, and starting again at 2 or 3 A.M., reaches Piura 

 before the sun has risen high enough to heat the desert. From 

 the tambo of Congora the ground descends for the remaining 

 seven leagues in gentle undulations towards the Piura (whose 

 valley has no steep limiting cliffs like the Chira), and the sandy 

 dunes at once begin, increasing in size and frequency as \\e 

 descend. These dunes, or medanos as they are called, are 

 notable for their lunate or half-moon shape, sometimes beautifully 

 symmetrical, and having their convex side towards the trade-wind. 

 They are continually shifting and advancing, but in general it is 

 necessary to watch them for weeks to appreciate their motion. 

 If a day's wind of more than usual violence disperse any of them, 

 then soon re-form to north-eastward ; a casual protuberance of 

 any kind a large stone or a mummified mule being a sufficient 

 nucleus for a new medano. On such days the sand which fills 

 the air has all the appearance of a dense fog, and indeed at Piura 

 the sky is generally more or less obscured from the same cause 

 between 2 and 5 P.M. of every da\. 



The medanos I have seen near Piura are only from 8 to 12 

 feet in height, and yet that is (mite high enough to render 

 it difficult for the horseman entangled among them to find 

 his way out, for one medano is almost the exact counterpart of 

 another. On the desert of Sechura, however, which is a vast 

 plain apparently depressed below the land immediately bordering 

 the coast, the sand is heaped up to a far greater height, and 

 I have been assured by an arriero that lie has found shelter tin r< 

 for the night, on the lee side of a incdano, for lu> companv ol ten 

 men, thirty to forty mules, and all their baggagi 



Ixjiit.i NOUS VEGETAI \< IN 



Any person, even one accustomed to the study ol and search 

 f"i plants, might travel through the \\liole extent of the deserts 

 of I'iura and Sechura, and (excepting the strip of verdure ah ng 

 the banks of the rivers) would confident!}- assert them io U- 

 entirely destitute of herbaceous vegetation; and yet three kinds 



