RECENT CHANGES OF ISSIK KUL. 
109 
THE RECENT CHANGES OF ISSIK KUL. 
The lake was lower and siiialler than it is now at a time not long past, as is 
shown by its recent invasion of the valleys that have been worn in the piedmont 
slopes. The low-water stand is believed to have been of later date than that of the 
Choktal moraine al)ove mentioned. The invasion of the valleys was not noticed at 
the western end of the lake. It was first seen in moderate development in the 
western quarter of the northern side, and became distinct a little farther east. It 
is described by Mr. Huntington as a notable feature of the east end of the lake, 
where the valleys, eroded in the sandy plain, are now drowned so far as to produce 
long, narrow bays. The scenery of the plain is dull and uninteresting, except for 
the \iews of the surrounding mountains ; but when one comes unexpectedly upon 
the drowned valleys, with their long, cur\-ing lanes of blue water and their green 
shores, the view becomes attracti\'e at once (fig. 73). Hence, like the erosion of 
the valleys, their drowning becomes more pronounced as we go from west to east. 
The contrast between the shorelines at the northwest end, the middle, and the 
northea.st end of the lake is strikingh- shown in the diagrams of fig. 74, which are 
reduced from the 2-verst map. 
The rise of the lake carried it to a higher level than that of to-day, but it 
remained there only long enough to cut or build a series of moderately developed 
shorelines, which were first recognized by Semenof in 1856, who .said that the lake 
seemed to have receded firom them, as if contracted 
in its bed (1858, 359). At the .southwest corner 
of the lake, where the bordering plain was low 
and marshy, we found a well-defined reef of small 
rounded pebbles, 3 or 4 feet high, 25 feet above the 
present shoreline, and a smaller sand reef at 10 feet. 
The present shore was marked b}- a low sandy 
beach or reef, often shutting in a narrow lagoon. 
At the northwestern comer of the lake, low reefs 
of sand or fine gravel were noted at heights of 2, 
3, 5, 10, and 25 feet. At Tur-aigir station, about 
15 miles from the west end of the lake, a 4-foot 
bluff stands about a quarter mile back from the 
shore, with its base 25 feet over the lake; and a 
beach was found 5 feet o\-er the lake. 
It was near Choktal station that we first noted 
that the raised beaches are of later date than the 
valleys. One example from man)- is illustrated in 
fig. 75. The surface of the piedmont slope is so smooth that the general shoreline is 
here notably even ; but a small point is made by a trail of coarse bowlders, some of 
which are 8 or 10 feet in diameter at a distance of 3 or 4 miles from the mountains. 
The valley here was 6 or 8 feet deep and 70 or 80 feet wide. The stony 25-foot beach 
or reef was prolonged directly across it, except for a little notch by which a small 
stream escaped. Se\eral lower shorelines were seen in the \-alley floor. In another 
Fig. 74. — Shorelines ot Issik Kul at the north- 
west end (A), the middle (B), and the 
northeast end (C) of the lake, reduced to 
18 versts to an inch from the 2-verst 
Russian map. 
