国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

~ 72   EXPLORATIONS IN TURKESTAN.

bounding a flood-plain so narrow that in the valley bottom a road with difficulty finds a place among the cedars and must often cross the cascading brook or even climb out of the valley. Between these young valleys the graded northern slopes

°c   ,. : xo N, of the broad anticline are covered with cedars, which form the

N      ,- â Tg .. only forest seen during the whole journey. Far up the stream,
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-,   here glaciers have been at work, the valleys widen and are

0   - s   better graded, and at the same time the interstream areas become

x   '   rougher, although they still contrast strongly with the valleys.

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5.   The youth of the latter is shown not only by the steepness of

0   ,'l ;   the walls, but by the relatively moderate depth, i,000 or 2,000

   '   feet, which seems to be the most that they have as yet attained

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~~   beneath the interstream highlands, although the streams descend
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g'   very rapidly and are cutting actively. Another evidence of youth

m is seen in a normal hanging valley from which a small side stream

I. o   cascades 4o or 5o feet directly into the Jukuchak Su, whose

0.

c   narrow valley here has no flood-plain whatever.

The broad ridge which lies along the northern border of the

   Fr §   l % 'N W

   H   Tian Shan plateau is always covered with snow, and most of its

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passes are occupied by glaciers. A few of the summits have

been sharpened into peaks by glacial action—after the fashion

   c   3 described for Alpine peaks by Richter—and are worth seeing as

a   ` r a attractive examples of Alpine scenery, but most of them are

   -â   mere remnants of the old peneplain, separated by broad, but not

s   very deep, valleys of glacial origin. The uniformity of summit

   d   height is illustrated by the excellent topographical map con-

   w   ; ...structed by the Russian general staff on a scale of 2 versts

   ~,   ; (/f â z (1 IZ miles) to the inch. Out of 43 summits, of which the

s•>!A, c , elevation was given on three contiguous sheets at the eastern eÇ: A s

   Ó~   t'.,   g end of Issik Kul, 32 reached an elevation of from 13,000 to

   ~.   f`; '   â , 14,000 feet, and the highest reached 15,069 feet.•

   _>   a   As soon as the broad ridge of the northern border is crossed
t;~, W the country assumes an aspect which fully justifies the term

   N    , t4   plateau." At Jukuchak pass, for instance, the narrow young

   ?c..   valley which one ascends in traveling southward from Issik
II

i;   Kul is exchanged for a broad, open, elevated plain, bounded

   .-.1   _

7.   11{ on all sides by snowy mountains, whose slight dissection
$` ; F. causes them to suggest a block of marble on which the sculptor

   co   .. _ L has rudely outlined a form but on which he has as et carved few

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"s I   ;"s details (see fig. 125). The treeless plain with its cover of brown

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11 or green grass has the thoroughly graded aspect and subdued

"   =   N slope of a region in late maturity ; and such it is in spite of its

Li-   „'. ti   elevation and potential youth. So far as erosion is concerned

a   r'r_ a

   :~..N;,   it only waits for some stream to cut headward through the sur-
I66ik Kul L. rounding ridges to cause it to enter upon a new cycle at the

ç    very beginning of youth. The Yak Tash basin, southwest of

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