THE QUATERNARY ERA IN SISTAN. 285 
carried water to the town of Haiizdar. Even now extreme floods of the Helmund rise 
high enough to trickle into it on rare occasions. All along the Shila and at the head 
of the God-i-Zirrah are abundant ruins, all of which seem to date from Mohammedan 
times. It is evident that the lakes of Sistan and Zirrah and the rivers of Helmund 
and Shila have undergone a series of changes intimately associated with the human 
historj' of the region. These changes seem to be explicable only on the theory' that 
the climate of Eastern Persia has been growing gradually drier during historical 
times. Before considering this question further we will examine certain phenomena 
which seem to indicate extensive climatic changes in earlier times. Having examined 
these, we shall be in a position to judge whether there is an adequate basis for the 
working hypothesis that the last pulsations of the series of climatic changes known 
as the glacial period are still in progress. 
THE QUATERNARY ERA IN SISTAN. 
THE DEPOSITS OF THE LAKE OF SISTAN. 
In the preceding pages the conclusion has been reached that while the more 
northern countries of the world were passing through a glacial period, Persia was 
passing through a fluvial period due to the same causes and characterized by a similar 
series of climatic oscillations. The record of the dry and wet or wann and cold 
epochs composing this fluvial period seems to be preserved in a series of terraces, 
lacustrine and fluviatile, which occur in all parts of the country. These terraces 
are unsatisfactory, because the record which they preser\'e is incomplete, and a single, 
strong, terrace-making impulse may destroy the record of all that have gone before. 
The best possible record would be one preserv^ed in the bottom of a basin which 
contained a lake during pluvial epochs, but was drj' or contained merely a playa 
during interpluvial epochs. Such basins abound in Persia, but the bottoms of most 
of them are not exposed for study. In Sistan, however, several volcanoes broke out 
during the latter part of the fluvial period, and parts of the lake bottom were warped 
upward to a maximum height of over 600 feet abo\'e the present lake level. These 
have since been undercut by the waves and fonn the bluffs which surround the lake. 
A proper interpretation of the sections exposed will disclose the history- of the lake 
far back toward the beginning of the Quaternary era. 
From a scenic point of view the most notable feature in Sistan is the lava- 
capped mesa of Kuh-i-Klioja (Mountain of the Teacher). P'rom whatever direction 
one approaches Sistan he sees a flat-topped hill, low and black, and nearly a mile in 
diameter. From the encircling reeds and water, steep slopes of dark talus mantling 
red clay rise 200 feet to the base of cliflTs of basaltic lava, over 200 feet high. The 
uneven upper surface of the lava is covered with many-chambered tombs, or is 
roughened with great pits, dug as reserv^oirs perhaps, or for some other unknown 
purpose. On the edges the lava is being undennincd by the retreat of soft underly- 
ing clays, and huge blocks are continually falling off, thus preser\-ing the steepness 
of the cliffs and hiding the strata below. Enough of the latter are seen to show 
that they are for the most ])art red, with some bands of green, and belong to the 
lacustrine series so well exposed elsewhere. At its contact with the lava the clay 
