,'SEIULAND 
. 127 
slope toward the Sierra Madre before it is condensed, and thus 
the region is arid. Streams rise in the high Sierra indeed, espe- 
cially during the midwinter and midsummer rainy seasons, and 
rush down the strong slope toward the gulf in roaring torrents ; 
but so diy are air and sand that even the largest floods are ab- 
sorbed well up the incline — and between mountain-born Colo- 
rado and sierra-fed Yaki, 500 miles apart, no river ever reaches 
the sea. The precipitation is greater on the outlying ranges, 
es})ecially the lofty masses of Seriland,than over the intervening 
plains ; yet everywhere tlie rainfall is so slight that the region is 
semidesert, with broad belts of Saharan sands between the coast- 
ward ranges. The local configuration about Seriland appears to 
favor local winds (rising into nearly continuous gales during De- 
ceml)er, 1895), and the unstable air brings forth fogs which feed 
the flora of coast and foothills ; but little moisture in rain, dew, 
or fog ever reaches that broadest of the desert plains of western 
Sonora, the natural boundary of Seriland, Desierto Encinas. So 
the aboriginal principality of Seriland is set apart, isolated, prac- 
tically insulated so far as life is concerned, hy a natural barrier. 
It is to this natural isolation, as well as to the ferocity of the 
natives, that the checking of exploration and evangelization at 
the Seri frontier is to be ascribed ; yet at the same time the char- 
acteristics of the savages are in a measure due to their isolation 
(as shown elsewhere), and thus natural condition and artificial 
custom have cooperated cumulatively through the centuries to 
])revent earlier study of the stanch little dominion of the Seri. 
The toi)Ography of Seriland is striking by reason of the rugged- 
ness of tlie ranges which rise steeply from great apron-like ex- 
]tanses of foot-slope or plain. The abrupt transition from jagged 
cliffs above to smooth ])lains below conveys irresistibly the 
impression that the mountains are buried to their ears in vast 
torrential deposits which line the intervening valleys to profound 
depths ; and the geologist is surprised and distrustful of observa- 
tion until many times repeated when he finds that the intermon- 
tane expanses are simi)ly ])laned rock strata with a scant veneer 
of torrent-spread alluvium. This tojiographic paradox, of which 
the wh(fie of Seriland and much of adjacent Pa))agueria form a 
great example, is well illustrated in a section exposed in the shore 
between Puerta Iidiermj and Punta Ygnacio. .A (piarter of this 
15-mile e.xposure is the current-built point, another (piarter cuts 
butte or range of igneous rock or ancient granite, while the remain- 
ing half traverses typical intermontane plain in clilfs of 20 to 50 
