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 we 
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 day. 
The medanos I have seen near Piura are only from 8 to 12 
feet in height, and yet that is quite 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 he has found shelter there 
for the night, on the lee side of a medano, for his company of ten 
men, thirty to forty mules, and all their baggage. 
Indigenous Vegetation 
Any person, even one accustomed to the study of and search 
for plants, might travel through the whole extent of the deserts 
of Piura and Sechura, and (excepting the strip of verdure along 
the banks of the rivers) would confidently assert them to be 
entirely destitute of herbaceous vegetation ; and yet three kinds 
