Proceedings of the Tomsk Technological Institute of Emperor Nicholas II.

Vol. XX, 1910, No. 4.

Geological Studies in Barlyk, Maily, and Dzhair in the Summer of 1909

(A brief report).

V. A. Obruchev.

During the summer of 1909 I continued, by assignment and at the expense of the Tomsk Technological Institute, the geological studies in the mountain ranges and deserts of Western Dzungaria that had been begun in 1905–06.

The expedition consisted, besides myself, of the Institute’s scholarship student in the Department of Geology, mining engineer M. A. Usov, who worked together with me on geological observations, and the student-technologist S. V. Obruchev, who carried out route eye-surveying and meteorological observations.

Having left Tomsk on 30 May, we arrived, via Omsk and Semipalatinsk, on 9 June in the town of Chuguchak, where, with the kind assistance of the Russian consul K. V. Luchich, our interpreter Gaisa Musin, a participant in the first two journeys, had already prepared the caravan equipment to such an extent that on 14 June we were able to begin work. The personnel consisted, besides the three of us, of the interpreter Musin, his son Abubekir, a Kirghiz worker, and two Kashgarian drivers; the means of transport were six riding horses and twenty pack donkeys; as needed, an additional guide was hired from among the Kirghiz whose nomad camps we encountered along our route.

From Chuguchak we headed south, passed the Emil River at the Manitu frontier picket, and the next day entered the northern foothills of the Barlyk Range, following the Tsagan-tokhoi River along the Russian border; from a camp at the beginning of the picturesque gorge of this river, which cuts through the Arasan volcanic massif, M. A. Usov made a separate excursion to the Arasan hot sulphur springs (which I had visited in 1905) and rejoined the caravan the next day, when we moved on to the Kogaly River, which still flows among the same flat northern foothills of the range, covered with a thick layer of typical loess. From Kogaly we turned east and began to ascend higher and higher over the rolling plateaus of Tyorya-dzhailau, Sary-choko, and Kok-choko, situated between the deep—

deeply incised gorges of the tributaries of the Tsagan-tokhoi River on one side and the Tasty River on the other; on the very first day of travel from Kogaly we climbed 1,000 meters and here encountered Kirghiz summer encampments; for the next two days the route lay at elevations of 2,000–2,200 m.

Across the Kyzyl-kiya pass, abs. elev. 2,500 m, in the Bisht-kura Mountains, which replace the indicated plateau to the east, we descended into the deep valley of the Tasty River, overgrown with beautiful spruce groves, and followed this valley to its headwaters, skirting from the east the jagged Kert-tau chain, the highest ridge of Barlyk, reaching the limits of perpetual snow. From the headwaters of the Tasty, through the headwaters of the Ush-kara-sai River, we crossed into the source of the Terekty River, flowing from the steep southern slope of Kert-tau; from there an ascent to the high part of the chain was planned, since we were already at an elevation of more than 2,500 m, while Kert-tau rises to 3,300–3,400 m. But bad weather set in, and Kert-tau for the second time refused to admit us to its jagged crest, upon which no explorer’s foot had yet trodden (in 1905 a visit to the chain had likewise failed because of bad weather). It was necessary to change the route and, while awaiting better weather, to make a seven-day circuit through the lower mountains situated in the interval between Kert-tau and the next ridge to the south, Maili, which separates the headwaters of the Kup River from the Dzungarian Gates; along the gorge of the Ush-kara-sai River, into the upper part of which a short but steep and broad glacier had formerly descended from the crest of Kert-tau, leaving several clear moraines, we descended to the marshy saz of the upper Kup River. At the northern foot of Maili we took on an experienced guide, a Kirghiz hunter who had more than once been on Kert-tau, and went westward down the picturesque Karagandy gorge, which opens into the Dzungarian Gates at the Russian border; along the eastern edge of the Gates we returned northward to the Dzhavlauly Mountains and, through lower high mountains among which the Sary-bulak River flows, again emerged at the Terekty River at the southern foot of Kert-tau, where we stopped at the Kyzyl-chilik locality, a little west of the first camp.

During this trip fine weather became established, and the ascent of Kert-tau was fully accomplished; we rode on horseback up a very steep path to a saddle on the ridge and then, along this ridge over continuous stone screes, rode eastward to the highest part—a broad and flat summit, on which the hypsothermometer indicated an elevation of 2,670 m above Chuguchak, i.e. about 3,320 m above sea level. Thanks to the cloudless sky and recent rains, which had cleared the air of dust, we were able to enjoy the panorama of the mountains

for a hundred versts around; to the south, behind the undulating plateau of Maily, one could just see the endless chain of Boro-khoro in the Eastern Tien Shan in the form of a row of sharp snowy peaks with intervening ice fields, from which we were separated by a distance of almost 200 versts in a straight line; to the north, beyond the yellow plain of Emil and Chuguchak, one could discern the wall of Tarbagatai, while to the west the masses of the Dzungarian Alatau showed blue; the view to the east was closed by the continuation of the Ker-tau ridge, on which there rose sharper summits, exceeding our camp by 50–80 meters. On the northern side of the ridge, in the cirques of the headwaters of the Kipeli and Chorchot streams, lay fields of melting snow, and old moraines could be seen, indicating the former glaciation of Ker-tau.

The southern slope of this chain, very short and steep, representing an undoubted escarpment, in places up to 1000 m high, did not favor the development of glaciers; only small tongues could descend here from the crest. On the contrary, the long northern slope, cut by deep gorges of the left tributaries of the river Tasty and other streams flowing independently westward, formerly contained a whole series of glaciers fed by the firn fields of the steep cirques of the valley heads and the flat heights of the ridge.

From Kyzyl-chilik we again headed south, through the already familiar low mountains west of the saz, and imperceptibly ascended to the surface of the Maily ridge, a rolling plain of absolute elevation about 2500 m, with Alpine meadows on which the Kirghiz summered; this plain, gently descending northward, breaks off steeply to the south toward a more southerly step of the ridge, which is 300–400 m lower and is covered with low hills and groups of higher mountains. Along this step we went for several days to the southeast, gradually descending ever lower, crossing the valleys of streams flowing southward and disappearing in the desert at the southern foot of the mountains; the valleys of these streams, which take their rise on the higher step of Maily, gradually cut ever deeper and in places turn into impassable gorges with a narrow strip of thickets of poplar, willow, various shrubs, and reeds along the channel, in which the water now appears, now disappears again. We passed the basins of the Laba and Suur rivers and came out to the Chalai River at the place where it breaks out of its gorge in the last chain of the ridge, but still flows through a deep canyon incised into the pedestal of Maily, composed of ancient coarse deposits, above which in places rise, in the form of smoothed hills, the bedrock formations composing the foundation of this pedestal.

From these hills to the south one could already see the desert with yellow patches of sand and a green sea of reeds along the Kuitun River, fed by the waters of the Tian Shan; the majestic chain of the latter, with snowy peaks and enormous glaciers, framed the entire southern horizon.

From the Chalgai River, where the absolute elevation is already only about 800 m, we turned northeast and again entered the mountains of the southern escarpment of the Maily, heading toward the Otsu picket on the great Chinese cart road from Chuguchak to Shikho, along which the telegraph runs; this road forms the boundary between parts of the same range bearing different names: to the west of it the mountains are called Maily, to the east—Dzhair. The direction of the road has been chosen very successfully; along the whole extent of the Maily—Dzhair this is the only place where there are almost no narrow gorges, where the ascents and descents are very gentle, because the mountains seem to draw apart on both sides, leaving a convenient space for a cart road. This strange belt, cutting across the entire range, is not an accidental phenomenon, but is connected with tectonics; for the most part it coincides with the axis of warping during disjunctive dislocations; the fault of the southern scarp of the high Maily escarpment to the east of this line passes into the fault of the northern scarp of the high Dzhair escarpment, so that the latter is the eastern continuation not of the upper Maily escarpment, but of the lower one; along this axis there are also two large granite massifs and ridges of effusive rocks, and rather large faults are visible, transverse to those indicated; therefore the crossing of the Maily—Dzhair by the Chinese cart road proved, contrary to expectations, to be extremely interesting and instructive.

We followed this road to the Yamatu picket, situated at the northern foot of the mountains; at the picket a transport with fodder, provisions, and mail, sent from Chuguchak, was already waiting for us and took back the collections gathered during the first month; several days spent at the picket for packing and unpacking the goods and for the mail made it possible to make further excursions in the surroundings for a better elucidation of the tectonics of this interesting place. From Yamatu we set out for Dzhair and quickly ascended along the gorge of the Karagaita River to the surface of the higher escarpment of this range, with an absolute elevation of about 1900 m, which, as in the Maily, is an undulating plain with alpine meadows; to the north this upland plain drops steeply toward the lowlands of the Kup valley, which separates the Maily-Dzhair

from Barlyk, toward the south, descends gradually, i.e. the reverse of what we saw at the higher escarpment of Maily, where the southern slope was precipitous and the northern one gentle.

Over the surface of Dzhair we walked for one day to the left summit of the Boguty River, where we turned southeastward down this stream, which gathers the waters from the entire traversed part of Dzhair; the character of the locality had much in common with the character of the lower escarpment of Maily: despite the gradual lowering of the absolute height of the mountains, the valley of the stream cut in ever more deeply, at places turning into a gorge difficult to pass, so that one had to leave the valley for the surrounding mountains in order to bypass inconvenient sections. In three days we had already descended to an absolute height of about 1000 m and arrived at the Ak-tam gorge, situated in a longitudinal tectonic valley laid out along the northern foot of the southern escarpment of Dzhair—the mountains Kyr and Chingiz—which, like the northern escarpment, breaks off steeply to the north and descends gently to the south, since on the north it is bordered by a fault. The already widened valley of the Boguty, crossing this escarpment, again turns into a gorge, and the road southward, to the valley of the lower Manas, climbs into mountains which in their composition are here very monotonous; therefore we turned east and northeast in order to cross the large granite massif of Kozhurtas, with the margin of which we had become acquainted in 1906. This massif occupies a considerable part of the area between the Boguty and Darbuty rivers on the southern slope of the northern escarpment of Dzhair and, owing to the easy disintegration of the granite, presents low mountains alternating with large and small closed basins and waterless valleys; the deep denudation of the massif, the abundance of outcrops, and the variety of veins cutting through the granite made it possible to become well acquainted with the features of the granitic massifs of Dzungaria in general.

Having passed the massif and its eastern schistose margin, we descended into the gorge of the Darbuty River to the same place where we had been in 1906; then we went farther northeast, to the southern foot of the rocky Katy chain, rising above the upper escarpment of Dzhair; from the camp at this foot my young companions made an excursion deep into Katy to the abandoned gold mines in the Belagach locality, and then we again turned southeast toward the lower course of the Darbuty River, through the desert low mountains of eastern Dzhair.

The lower reaches of the Darbuty proved very interesting; the river flows for several tens of versts along a fault, which caused

the steep northern precipice of the southern scarp of Dzhair, which we had left at the Aktam locality on the Boguty River; the river valley is cut into a gorge which for an entire verst stretches in a straight line, crossing various rocks—several small masses of pyroxenite, transformed into serpentinite, and their schistose envelopes, as well as a rather large granitic massif; in the latter the gorge becomes winding and completely impassable, but the surface of the massif is a plain over which one can ride without even suspecting that nearby a deep and picturesque canyon has been cut. After emerging from the latter, the Darbuty, for some twenty versts, again flows in a straight line along the continuation of the same fault; but the mountains here become ever lower, turning into bare, almost black, schistose hills, and the river (or rather its dry bed, since in summer water is found only in places along the whole lower course of the Darbuty) emerges from Dzhair into the desert separating this range from the Dama River.

We still had to visit the lower reaches of the Dama and the desert ridges between this river and the Kobuk River before turning back to Chuguchak; therefore we crossed the desert, crossed the Dama at the place where it cuts through the western end of the Kara-arat ridge by a small gorge, and descended into the Orkhu (or Urkho) basin—a large oasis amid the desert, with groves of poplars, thickets of reeds, fields, and even the farms of Kalmyks (Mongol Torguts). In this basin the Dama had formerly divided into two parts: one part of the water flowed north, emptying into Lake Ulustu-nor, the other part flowed south into Lake Airik-nor; P. K. Kozlov’s expedition, which passed here in 1891, mapped both these lakes. But gradually the northern channel became clogged, the water ceased to reach Lake Ulustu, which had already dried up about fifteen years earlier; now it is a bare clayey plain, smooth as a table and completely dry; but patches of dried reeds along the margins, shore terraces, lines on the cliffs, and beach ridges testify that there really was formerly a lake here, about 10 versts in diameter.

In the Orkhu basin we spent six days in order to study an interesting aeolian city, or rather the ruins of an extensive city created by the activity of aeolian agents; this city had been discovered by us in 1906, but at that time we did not have time to examine it in detail; now, however, the study of this place was included in the expedition’s program.

The Orkhu basin and the lower reaches of the Dama River are cut into a thick series of Upper Mesozoic or Tertiary soft sandstones and clays, easily

washed away by rains and blown apart by winds; to the east of this basin a considerable part of the suite has already been destroyed, and the remnants resemble the ruins of an enormous city, occupying an area of several tens of square versts. We crossed this area in various directions, surveyed it by eye, took about a hundred photographs of the original forms of weathering, and studied the beds of this suite in sufficient detail; but, despite the abundance of exposures amid the strongly dissected terrain, only at one point was it possible to find several specimens of fossil shells, apparently freshwater ones, which may perhaps make it possible to determine the age of the suite, which is more recent than the Mesozoic of the foothills of Urkashar and Dzhair.

Having finished our study of the Golden City, we moved to the Ulusty spring and examined the bed of the former Lake Uluglyu-nor, and then crossed the desert ridges of the Kara-arat range and the broad belt of desert separating this range from the more northern Kara-serke range; from the camp at the western end of the latter an excursion was made into the mountains, and then we turned westward and, on the way to Dyama, also visited the small Seinyk range, rising in isolation amid the desert and consisting of ancient schists and igneous rocks, over which folds of strongly dislocated Mesozoic deposits have been thrust; in the latter, near Kara-serke and near Seinyk, plant remains were found.

Having passed the Dyama River, we moved along a belt of oases at the southern foot of Urkashar and, during a stop near Mount Bogo-mainak, which forms the southwestern spur of this ridge, discovered the presence of typical moraines, proving the former strong glaciation of Urkashar. Then we passed through the low Dzhildy-kara mountains, situated between Urkashar and Barlyk, skirted the eastern end of the latter, and, over a new pass, crossed to the northern side of Barlyk in order to visit the mouth of the valley of the Altyn-emel River, where in 1905 we had found Paleozoic fossils, among them trilobites, whose collection it was desirable to supplement. The further route lay along the northern foot of Barlyk, via the Kara-bura River, which has cut a deep gorge into a mass of volcanic tuffs and breccias, to the Dzhar-kura valley, where good outcrops of Upper Tertiary Hanhai deposits were found, which occur comparatively rarely in the part of Dzungaria investigated.

From this river we headed north straight to Chuguchak, finishing along the way the study of the northern foothills of Barlyk; on August 29 we were in Chuguchak, and on the 31st we already left from there, and the detachment

postal horses on the road as far as Semipalatinsk and the shallows of the Irtysh between Semipalatinsk and Omsk forced us to spend 2 weeks on the return to Tomsk.

Thus the journey lasted \(3 \frac{1}{2}\) months (from May 30 to September 13), while the actual field work lasted \(2 \frac{1}{2}\) months. In addition to an extensive collection of rocks and fossils, the results of the expedition include a route-and-visual survey of the entire path, 317 photographic shots, hypsometric determinations of 219 points,*) and meteorological observations.

Since the materials collected are already being processed and a description of the journey is being prepared for publication, in the present report I shall confine myself to the very briefest data on the orography and geological structure of the part of Dzungaria investigated.

Like the Kodzhur, Urkashar, Semistau, and eastern Dzhair studied in detail in 1906, the Barlyk, Maily, and western Dzhair ranges represent a complex of high plateaus at 1000–2000 m absolute elevation, with a more or less even surface covered by alpine meadows, steeply cut off and deeply dissected along the margins; above the surface of these plateaus there rise in places, as if planted upon them, ridges, which represent higher and narrower areas, strongly cut up by denudation processes and transformed into ranges; such, for example, are the Ker-tau mountains in Barlyk, reaching 3300 m absolute elevation, the lower Sarkamyr and Kuu-karagai there as well, Katu in eastern Dzhair, and others.

In geological composition the localities investigated do not differ essentially from the previously studied parts of the same mountain system; it is necessary only to note the special distribution of the Devonian, apparently of various divisions, in places—especially in Barlyk—rich in fossils. Mesozoic and Tertiary deposits, developed in the valley between Urkashar and Dzhair, have the same character as in the region of the former investigations; the same must be said of metamorphic schists and massive crystalline rocks; among the latter granites are especially widespread; the enormous masses of this rock, discovered in 1906 in eastern Dzhair, pass also into the western part of these mountains, but west of the Chinese postal road, i.e. within the limits of

*) I take this opportunity to express my deep gratitude to Consul K. V. Luchich, who took upon himself the trouble of recording the aneroid readings in the town of Chuguchak during our journey, which gives me a reference point for calculating absolute elevations.

Maily, occur much more rarely and are smaller in size; in the eastern part of Barlyk and in the northern foothills of this range granite appears again.

The new investigations confirmed the previous conclusions concerning the predominance of disjunctive dislocations and the enormous significance of the latter for the present-day relief: the plateaus of Barlyk, Maily, and western Dzhair represent the same complex step-like horsts as Urkashar and eastern Dzhair, while their surface, approaching the “pene-plain” type, is likewise cut across rocks of varied composition, differing hardness, and different conditions of occurrence; it is interesting to note once again that in Dzhair the Darbuty River, in its lower part, flows for many versts in a straight line along the fault fissure that bounds the northern escarpment of the southern of the horsts of Dzhair—the Chingiz Mountains. In the area between the Kara-serke Range and the Dyam River, very strong folded dislocations of Mesozoic deposits were also found.

Signs of former glaciation were encountered in the highest part of Barlyk—the Ker-tau Mountains—and on the southern slope of Urkashar; Ker-tau even now is free of snow for only 3 months, and in sheltered places snowfields lie until the end of July; but formerly glaciers descended from this range in all directions, ending at an absolute altitude of about 2000 m, and in places even lower. Still larger cirque glaciers, fed by extensive firns on the even surface of the southern scarp of Urkashar, descended southward, reaching the plain at the southern foot of this range at an absolute altitude of 1000–1200 m.

Of the useful minerals in the region investigated, only deposits of ore and placer gold were encountered in the northern part of eastern Dzhair, some of which had already been visited in 1906; the deposit of vein asphalt on the Dyam River in the Orkhu depression was also visited again.

V. A. Obruchev.

Tomsk,
10 November 1909.