Untitled - The Alfred Russel Wallace Website

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 it general is
their motion.
necessary to watch them for weeks to appreciate
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
the banks of the rivers) would confident!}- assert them
ah ng
io Uentirely
destitute of herbaceous vegetation; and yet three kinds