222 THE BASIN OF EASTERN PERSIA AND SISTAN. 
books, and also the most recent, is that of Major Sykes, "Ten Thousand Miles in 
Persia," a work which embodies a vast amount of careful observation and record, 
supplemented by most painstaking research. To it and to others of the same class 
which are noted in the bibliography at the end of this report, I shall have more or 
less occasion to refer. Lord Curzon's " Persia " stands easily first among books on 
the country as a whole, but unfortunately it deals but briefly with the eastern part 
of the Shah's dominion, and hence will be referred to but little. Of books by pro- 
fessional geographers or geologists, there is, so far as I know, not one which deals 
with, Sistan and the most important parts of Eastern Persia. Hlanford, liowever, 
over thirty years ago, traversed the neighboring regions to the south and west, and 
has given ns the result of his observations and studies in a valuable review of the 
geology of Persia as a whole, and in a masterly essay on that most striking of Persian 
physiographic phenomena, the huge gravel fans at the base of the mountains. 
More recently Vredenburg has written a geological account of the portions of Balu- 
chistan to the south and east of Sistan. His facts are valualjle, althougli some of 
liis conclusions are open to question. In addition to the classes of books already 
named there are several accounts of Eastern Persia wliich are mere travelers' tales of 
the most ephemeral interest. The books of all classes, so far as I have consulted 
them, are mentioned in the bibliography at the end of this report, although not all 
are referred to in the text. As an aid to future students a brief comment on the 
nature of the work is appended to each title in tlie bibliography. 
OUTLINE OF THE FOLLOWING REPORT. 
Eastern Persia is one of the most desolate lands in the world. The chief cause 
of its desolation is aridity, due in the first place to the countr>-'s continental position 
and in the second to its basin character. As a result of Persia's continental position 
the prevailing northwest winds which blow across it have not only alread)- traversed 
witle stretches of land and been deprived of most of their moisture, l:)ut the)- are con- 
tinually advancing into more heated regions and thus becoming wanner and less 
ready to part with moisture. The basin character of the country tends to increase 
the dryness of the interior ; for the mountains which snn"onnd the basin are for the 
most part lofty and cau.se the precipitation of whatever moisture the winds may 
still contain after their long journey from the sea, so that almo.st nothing is left for 
the inner regions. 
Eastern Persia, northwestern Baluchi.stan, and southwestern Afghanistan are 
all included in the basin which has just been mentioned. Close to the eastern 
border of Persia this basin of Iran, as it is called, is divided into two snl)sidiary 
basins by a range of mountains running north and south. (See sketch map, fig. 
152.) East of the range, and complementar)' to it, lies a remarkable dejires- 
sion containing the Heri Rud River and four large hollows containing playas or 
saline swamps. (See map at end of volume.) Although the geological history of 
the countr}' is imperfectly known, the unconformability between Tertiary- deposits of 
continental or estuarine origin and Cretaceous deposits of marine origin shows that 
Iran began to assume its present basin form far back in the Tertiary era. Since 
