62 EXPLORATIONS IN TURKESTAN. 
to Seuiipalatinsk, July 28 to August 2, in several headwater valleys of the Karatal, 
a river that flows into the mid-southern side of Lake Balkash from the western 
spurs of the Cis-Ili Ala-tau. Near the village of Kugalinsk (see sheet 12 of the 
40-verst Russian map), the northwest slopes of the Chulak range were cloaked 
with grassy loess and somewhat dissected 
by small consequent valleys, across which 
the road had many ups and downs. On 
the ridge between Kugalinsk and Tzarat- 
zinsk the slopes are strewn with irregular pig. 35.— Diagram of Loess Drids. near Kara-bulak. 
mounds of loess of small relief, in which looking south. 
the roadside cuts were creamy white. The 
surface was well covered with grass ; hay had been cut in places. On the ne.xt 
ridge, which divides the Kok from one of its branches, there was a curious mixture 
of fresh and hackly ledges and smooth mounds of loess, in which some road-cuts 
were 10 feet deep. The mounds seemed to have a trend from the northwest or 
west-northwest, and occurred up to altitudes of 4,000 or 4,500 feet. 
The valley of the Kusak, near Kara-bulak village, afforded the most significant 
features, for here the drifted form of the loess became verj' pronounced. The vallc)- 
floor, at an altitude of about 2,800 feet, very smooth and about a mile wide, opens 
westward between long spurs descending from the range on the east. The stream 
has cut a narrow trench, 20 or 30 feet below the floor, along the base of the northern 
spur. The current is rapid, with large cobbles on its banks. A few miles to the 
west the trench opens on a broad, fan-like plain, where the road was very rough 
from the abundance of rolled stones. The valley-side spurs were covered with loess 
drifts, hundreds of feet in length, thinly overgrown with herbage, somewhat 
barkhan-like in form, gracefully convex in their longer ascent from the west and 
falling off steep to the east ; crowded together and overlapping like a school of fish 
hurrying upstream ; more closely packed to the west, and thinning out to the east. 
Their form is too systematically drawn in fig. 35. The difference between these 
aggraded drifts and the normally dissected slopes of the spurs of country rock 
farther up the valley was very striking and suggestive. The latter had all the 
down-hill lines that indicate the work of ordinary erosive forces, and repeated the 
ravined forms so familiar elsewhere. The former showed no sign of down-hill 
grading, but expressed most clearly the sweeping of the wind over their graceful 
curves. Hence, unlike the deposits near Samarkand and Tashkent, the loess here is 
of so recent a date as to be uuchanneled. It preserves most perfectly its wind- 
swept form; it may still be growing. The phrase, "wind-swept form," is used 
because, although the loess drifts are now covered with scanty herbage, the profile 
of the drifts, gently convex to windward and falling more abruptly to leeward, 
suggests that the actual motion of the wind has had nuich to do with shaping 
them. As to the constitution of the drifts, we had the most convincing evidence 
while descending across them on the southern side of the valley. An impalpable 
white dust was raised in a blinding, smothering cloud by our galloping horses and 
rolling wheels ; and the penetrating power of the dust here and elsewhere was 
