REPORT

(PRELIMINARY)

ON A TRIP

TO THE MUGODZHAR AND GUBERLIN MOUNTAINS.

Professor M. Yanishevsky.

Tomsk.

Steam Typo-Lithography of P. I. Makushin, Blagoveshchensky Lane, own house.

1905.

Printed by order of the Director of the Tomsk Technological Institute of Emperor Nicholas II.

REPORT

(Preliminary)

On a Trip to the Mugodzhar and Guberlin Mountains

By Professor M. Yanishevsky.

In the summer of 1904 I was sent by the Tomsk Technological Institute to the Mugodzhar and Guberlin Mountains for geological investigations. In view of the scant study and comparatively poor accessibility of the Mugodzhar Mountains, which lie in the desert part of the Ural and Turgai regions, I proposed that my brother, the botanist and Privatdozent of Kazan University D. E. Yanishevsky, take part in the excursion to the Mugodzhars, since it was very important to touch upon the indicated locality also from the geobotanical side. In addition, the excursion party included N. G. Kozhevnikov, a student of the Tomsk Technological Institute. With such a composition, the work of studying the locality in its natural-historical aspect could be divided. Kozhevnikov and I were occupied chiefly with geological investigations, while my brother carried out geobotanical and partly zoological investigations. In addition, I incidentally carried out a barometric survey as well.

The route of our excursion was as follows. Having assembled in Samara on May 25, we set out by railway to the city of Orenburg. Having stocked up here with many necessities and hired a servant, we proceeded along the Orenburg–Tashkent railway, then under construction, in the direction of the Mugodzhars. Thanks to the kindness of the builder of the northern section of the indicated road, engineer A. I. Ursati, we received at our disposal a specially fitted fourth-class carriage, which we were able to use throughout the entire excursion, moving along the railway line and making stops at the points most interesting to us. As it turned out, this carriage was very useful to us and considerably eased the tasks of our excursion. In that desert locality through which the railway passes, it served as our main quarters, where we could keep

the collected scientific material and where we could find the necessary rest during the excursions. Before reaching the Mugodzhar, we, taking advantage of the opportunity afforded us to make stops at any point on the railway, examined a comparatively large area and collected a rather large amount of scientific material.

We made our first stop at st. Aksu, or Martuk, situated on the right bank of the river Ilek, a tributary of the Ural River. This stop enabled us to make side trips in order to survey the Mesozoic deposits exposed here. Thus, having crossed the river Ilek, we were able to examine the banks of the latter’s tributary—the Aksu—with its tributary Kurocha, and to become acquainted with the Jurassic deposits exposed near the latter. The next stop was made by us at st. Ak-Bulak, whence an excursion was made, 10 versts upstream along the river Ak-Bulak, to examine the exposures of white chalk. Then we made a stop in the town of Aktyubinsk, and from there made side trips in the environs of this town, along the system of the river Tiris-Butak, to examine Permian, Permo-Carboniferous, and Jurassic deposits. The following stops were made by us at the stations Dzhurun, Izembet, and Emba. These last stops gave us the opportunity to survey the environs of these stations and to become acquainted with the Cretaceous deposits exposed there.

Finally, the next two stations at which we made extended stops were: st. Mugodzharskaya, situated near the western slope of the Mugodzhar, and st. Ber-Chugur, situated near their eastern slope. These stations served for us as starting points for more or less prolonged side trips into various parts of the Mugodzhar. In addition to small one-day excursions in the environs of these stations, we made prolonged excursions to examine more distant points of the central and southern parts of the Mugodzhar. Thus, one excursion was made by us from Mugodzharskaya station through a pass situated somewhat south of the railway line, in the direction of the town of Alabasa. Another excursion was made to the same place, but the crossing of the Mugodzhar Range was made along another line, lying somewhat north of the preceding one. A third excursion was made from Mugodzharskaya station in the direction of st. Ber-Chugur and farther to the NE in the direction of the town of Shuldak; after examining this mountain, we returned past the town of Alabas to Mugodzharskaya station. A fourth excursion was made by us to the town of Airok, which represents the highest point among the Mugodzhar Range. The fifth excursion, the most prolonged, was made by us from st. Mugodzharskaya along the western slope of the Mugodzhar, past Airok, to

the region lying north of the Ayruk, namely toward the headwaters of the rivers Ak-tübe-Aulie and Kunduzdy, the crossing to the eastern slope of the Mugodzhar being made over the elevation Dau-dän-tau, and then the locality along the eastern slope of the Mugodzhar was examined by the road past the town of Shuyldak as far as the station Börö-Chugur. The sixth excursion was undertaken from the station Börö-Chugur, along the railway line, in the direction of the station Karagandy, whence a detour was made into the southern part of the Mugodzhar, toward Mount Yaman-tau, and a new traverse was made across the Mugodzhar ridge to the west. After examining the environs of Lake Ak-kul, we returned to the Börö-Chugur station, but by a new road. In addition, we specially examined numerous cuttings along the railway line between the stations Mugodzhar, Börö-Chugur, and Karagandy. After examining the middle and southern parts of the Mugodzhar and after a short excursion to Lake Chelkar, lying east of the Mugodzhar near the Bolshie Barsuki sands, we proceeded along the railway line to the town of Aktyubinsk. Having made the necessary provisions there, we, together with the horses and carts hired there, went by the same railway to the station Izembet, where at last we parted with the carriage assigned to us. From Izembet station we set out in a north-easterly direction for Yaman-Uryuk, whence we rode into the northern part of the Mugodzhar through the headwaters of the river Chili, a tributary of the river Ori, toward the mountains Karatau, Ak-Chuchak, and Cheke-Karatau; here a new traverse of the Mugodzhar ridge was made. Having traveled around the northern part of the Mugodzhar, we proceeded to the headwaters of the river Ori, and from there turned onto the post road leading from the town of Kazalinsk to the town of Aktyubinsk. This concluded our excursion in the Mugodzhar.

We made our detours away from the railway line on horseback, and always had at our disposal two carts; in this way we were able to carry out geological and botanical observations separately, although our routes were common.

In the town of Aktyubinsk our excursion party divided: I, with Kozhevnikov, went to the town of Orsk, while my brother went to the town of Uralsk. During the journey from Aktyubinsk to Orsk it was possible to trace in detail the section of various sedimentary and partly volcanic rocks composing that belt which lies in the interval between the Mugodzhar Mountains and the southern Urals.

From the town of Orsk we proceeded to the so-called Guberlin Mountains—a mountainous region situated in the southern part of the Urals, in the basin of the river Guberlya, a tributary of the river Ural. On the way there, our attention was ...

it was concentrated chiefly on the outcrops of Carboniferous limestone, appearing as a small island to the east of the Guberlin Mountains (properly, the Khabarny Mountains), not far from the settlement of Khabarnaya. In the Guberlin Mountains themselves we made an excursion from the settlement of Guberlin along the river Chebakla to the N, and then, turning toward the settlement of Sara and farther east past the river Koyla, returned to the settlement of Khabarny. In addition, we examined the locality along the road running from Khabarny to Guberlin. After this we set out along the Orsk road to the town of Orenburg. This concluded our excursion in the Orenburg region. Altogether, this entire excursion (to the Mugodzhar and Guberlin Mountains) took us about \(2 \frac{1}{2}\) months.

I used the remaining part of the summer to visit several points of interest from a paleontological standpoint, in order to collect paleontological material; namely, to visit the village of Myachkovo—not far from Moscow—and the village of Roiki on the Tom River in the Kuznetsk district of Tomsk Province. These two points made it possible to collect considerable material from Carboniferous deposits.

At present, part of the collections gathered during the excursions is already in the paleontological cabinet, while another part is still on the way.

In the further account of the observations made during the excursions, I shall dwell separately on several regions that served as the subject of geological investigations. First I shall dwell on the locality lying to the west of the Mugodzhar, then on the Mugodzhar themselves; further, on the locality situated in the interval between the Mugodzhar and the Urals, and finally on the Guberlin Mountains. In this brief report I shall necessarily have to confine myself to the very briefest information concerning the geological facts observed, leaving their detailed exposition for the detailed report, to which a botanical report will also be appended.

Locality lying to the west of the Mugodzhar

The locality lying to the west of the Mugodzhar is partly a hilly area (nearer to Orenburg), partly an even steppe expanse, bearing to a considerable degree traces of prolonged denudation. Evidence of the latter may be seen in the broad valleys of the rivers, of which the most significant here are the Ilek and the Emba, with their numerous small ...

tributaries. Broad river valleys could have formed here all the more easily because the rocks composing the indicated area include, to a considerable extent, loose sandy and clayey rocks. The bedrock composing the locality under consideration is represented by Permo-Carboniferous, Permian, Jurassic, and Cretaceous formations. Permian deposits were observed by us near the town of Orenburg and farther along the railway line as far as the town of Iletsk, and also in the environs of the town of Aktyubinsk along the river Yamant-Kargala and its tributary—the Tiriss-Butak. These deposits are represented by various rocks—limestones, marls, sandstones, and conglomerates—and belong partly to the tier of variegated marls (the town of Orenburg and the sections of the railway closest to it), and partly to the red-colored series, which should presumably be regarded as the lower division of the Permian system (environs of the town of Aktyubinsk). Unfortunately, no well-defined organic remains were found in the latter series, except for poorly determinable Nayadites. In the environs of Aktyubinsk, namely along the rivers Yamant-Kargala with its tributary Tiriss-Butak and Yakshi-Kargala with its tributary the river Chikili, a Permo-Carboniferous series was encountered, represented here by gray sandstones and gray clays, often with considerable deposits of gypsum. Incidentally, the presence of the latter accounts for the existence, within the area of distribution of the indicated deposits, of numerous sinkholes. These deposits in the environs of Aktyubinsk have been displaced from their horizontal position and have a prevailing strike from NNO to SSW.

Jurassic deposits were observed by us along the Kuroch River, a tributary of the Aksu River, which flows into the Ilek River from the right. Here, on a broad, gently sloping slope to the left of the river, it was possible to trace several separate beds arranged one above another. Unfortunately, there is no good section here, and the existence of individual beds could be judged from separate pieces of various rocks occurring at different horizons in the surficial brownish clayey bed. In some cases the pieces of rock are completely filled with fossils, which occur within the surficial clayey bed also in isolated form. Despite the absence here of a good section, it was nevertheless possible to establish that the lower part of the Jurassic deposits exposed here consists of greenish-gray sandstones with Cardioceras alternans Buch and Gryphaea dilatata Sow., while the upper part is formed by beds with Aucella cf. Pallasii Keys. In addition, judging by rounded pieces of limestone with impressions of Cardioceras cordatum Sow., found near the Kuroch River itself, these beds are also present here. Thus,

It is an undoubted fact that an Oxfordian stage exists at the indicated locality. Jurassic fossils were also encountered at another point, but already in secondary position, namely in the environs of Aktyubinsk, along a small ravine flowing into the river Tirist-bulak on the left. Here, beneath a layer of yellow-brown post-Pliocene clay, a brownish-gray sandstone crops out, the beds of which dip at an angle of about \(45^\circ\) to the NW. At the boundary between the clay and the sandstone, precisely on the bottom of the ravine, rolled pieces with Jurassic fossils occur in large quantity. This fauna has not yet been determined, but judging from the fact that there occur here Belemnites, most likely belonging to the species Panderianus d’Orb., and Trigonia, close to Tr. clavellata Sow., these forms probably belong to the Kelloway or Lower Oxford.

The Cretaceous formations have their greatest development in the locality situated to the west of the Mugodzhar. These formations are represented by rather diverse deposits: white chalk, glauconitic yellowish-greenish sands, loose and firm sandstones, hard quartz sandstones, opokas, and brownish-gray clays.

White chalk was discovered by us only at one point, namely along the Ak-bulak River—the right tributary of the Ilek River, 12 versts north of the Akt-bulak railway station. Here there is a rather considerable area occupied by outcrops of white chalk, already from afar striking the eye by its white color. The following forms were found here: Ananchytes ovata Lesk., Belemnitella lanceolata Schl. (many), Terebratula carnea Sow., Ter. obesa Sow., Terebratulina gracilis d’Orb., Rhynchonella plicatilis, var. octoplicata Sow., Lima sp., fragments of Inoceramus, remains of fish, and others. These forms testify to the Senonian age of the indicated chalk. Incidentally, the complete similarity of this chalk to the chalk cropping out near the town of Volsk on the Volga River is noteworthy.

Glauconitic sands and loose sandstones, and in part opokas, crop out at a far greater number of points along the railway line. Thus, they are observed beginning from the station Dzhurun, and are visible everywhere both in cuttings and in the bluffs of the elevations lying on either side of the road, as far as Izembet station and farther to the 403rd verst of the railway. These sands are also visible away from the railway line, for example to the northeast of Izembet station—on the right bank of the Kublei-Temir River. Far from always do they alone enter into the composition of one or another section; rather, they often alternate with clays. To judge the nature of such bedding one may cite

one section, observed on the right bank of a small river near Izembet station:

g) fine greenish-brownish-gray glauconitic sand with a mass of Ostrea vesicularis Lam., Belemnitella mucronata Schl.; in the lower part sponges were found: Ventriculites cervicornis Goldf., Caeloptychium Goldfussi Fisch., Ventriculites sp., etc.; thickness . . . . . 1–1½ sazh.

f) dark-gray fissured clay with gypsum . . . 1½ arsh.

e) greenish sand and dark clay . . . up to 1½ arsh.

d) light-yellowish-gray dense sand . . . about 1 sazh.

c) phosphorite interbed

b) grayish loose sandstone . . . about 2½ sazh.

a) clayey bed of undetermined thickness

In bed b there were also found Belemnitella mucronata Schl., impressions of Nodosaria, tubes, fish scales, etc. The strata apparently lie horizontally. Rocks of the same character also crop out to the NE of Izembet station, along the Kublei-Temir River. Only here, in the lower part of the section, beneath bed a, there is also visible a light-gray clay interbedded with micaceous dense sand containing remains of dicotyledonous plants.

Toward the east, sands and sandstones gradually give way to gray gypsum-bearing clays. Thus, for example, this is visible near Emba station. Incidentally, here, near the station, a rather varied fauna of small mollusks was discovered in the gray clay, but it is in rather poor preservation. Among this fauna it was possible to identify the genus Baculites, but a more detailed determination has not yet been possible.

Farther east, already near the foothills of the Mugodzhar, in various localities, a compact quartz sandstone with indistinct traces of plants crops out. Judging from the fact that to the east of it, in some localities, sandstone with an unquestionable Cretaceous fauna (Inoceramus, Baculites, etc.) was found, and judging from the fact that the general, though slight, dip of the rocks is approximately to the W, the compact quartz sandstone must be assigned to the Cretaceous system. It crops out over especially considerable areas near Mugodzharskaya station, where it is also quarried for the needs of the railway. It is likewise strongly developed northward in the so-called Yaman-Urkach, where, on weathering, it gives rise to barkhans.

In addition to the rocks mentioned, west of the Mugodzhar white rocks are developed to a considerable degree, partly containing gypsum, which, upon closer study, proved to be tripoli. It is in the form of

a series of elevations stretch along the western slope of the Mugodzhary, at some distance from the latter, and even from afar they are sharply noticeable by their white color (so that from a distance they may be taken for white chalk). Incidentally, they bear sharp traces of erosion. They are cut in every possible direction by cracks, in which brown iron oxide has been deposited. Their age cannot yet be precisely determined, since no organic remains have been found in them except diatoms, which require special study. Most likely it is of Cretaceous age, since there are facts indicating that they occur among Cretaceous rocks (for example, near Lake Ak-kul, SW of Mugodzharskaya Station).

As indicated above, the Cretaceous deposits lie almost horizontally, with a slight dip to the west. In addition, there are facts indicating their unconformable superposition on Devonian deposits (at some points of the western foothills of the Mugodzhary). This indicates that they were not affected by the dislocational processes that resulted in the Mugodzhar Mountains. It must be supposed that they were deposited long after mountain-building activity had ceased in the Mugodzhary region and in adjacent areas, since the Jurassic deposits, apparently, also lie unconformably on the Permo-Carboniferous deposits, as may be concluded from the above-mentioned case of the occurrence of eroded Jurassic deposits on inclined gray sandstones (see above, p. 6).

Mugodzhary.

The Mugodzhary lie between 49½° and 48° N latitude. Beginning in the north near the sources of the Or River, a tributary of the Ural, they extend in a narrow ridge almost in a meridional direction to the south, gradually narrowing, and end at Mt. Yamantau. Farther to the south lies a lower area separating them from the Ust-Urt upland. The height of the Mugodzhary is generally not considerable; suffice it to say that the highest mountain belonging to this range—Airok—reaches a height of 1,890 feet above sea level (according to Tillo’s measurement). But these mountains stand out rather sharply above the adjoining terrain, which is a more or less level desert steppe. Owing to the latter circumstance, from afar, 40 versts away, they are clearly visible on the horizon as a range stretching from N to S and having a more or less sinuous crest. Already from afar it is evident that Airok noticeably

stands out above the other elevations making up the range, and even from afar it is already noticeable that the Mugodzhars, lowering toward the south, ultimately break off in the south, beyond which a lowered expanse extends.

Although in their basic features the Mugodzhars are quite simply constructed, representing folded mountains, their relief is rather complex. This is explained to a considerable degree by the fact that a very large part in their composition is played by various volcanic rocks; moreover, their relief has been affected by the prolonged action of denudation processes. The Mugodzhars serve as the watershed between the basins of rivers flowing partly into the Caspian Sea and partly into the Aral Sea. On them originate the rivers Chili and Tashla-Or, which flow into the Or, a tributary of the Ural River; farther on, the rivers Dzhalagash, Kyunduzdy, Ak-tyken, and Karagandy, which flow into the Emba River; of the rivers flowing eastward, the Tolen, Kaindy, and Shuldak originate on them and flow into the Chit-Irgiz, a tributary of the Irgiz River, as does also the Kaulzhur River, which gradually loses itself toward the SO in sandy deposits. In addition, many ravines originate in the Mugodzhars, flowing into one or another of the rivers named above. In general, the Mugodzhars present a rather cheerless picture. Their main mass is devoid of significant vegetation, which has found shelter chiefly in the small ravines cutting their slopes. The summits of the mountains themselves are stony and covered only with scant vegetation. Even in the ravines water could not always be found, and meanwhile the question of water, in so hot a climate as is observed there, is very important and at times may assume a very acute character.

The Mugodzhars had previously been touched upon by geological investigations. Thus, their geological structure was dealt with, to a greater or lesser extent, by Hoffmann, Severtsov, Borshchov, Helmersen, and Yakovlev, among others. In 1889 an expedition was sent there by the St. Petersburg Society of Naturalists, whose members included Venyukov and Levinson-Lessing. Finally, in recent years, during the construction of the Orenburg–Tashkent Railway, the Mugodzhars attracted the attention of Nikitin, a member of the Geological Committee. These persons shed much light on the geological structure of the said mountain range, which, of course, greatly facilitates its study.

The Mugodzhars are formed both of sedimentary and, to a considerable extent, volcanic rocks.

A. Sedimentary Rocks.

Among the sedimentary rocks, Devonian and Carboniferous deposits take part. The Devonian deposits are represented by rather varied rocks: here, to a considerable extent, there are limestones of various kinds, calcareous conglomerates, sandstones, argillaceous and siliceous shales. These rocks are represented quite unevenly in different parts of the Mugodzhar Mountains and enter chiefly into the composition of the western and eastern foothills of the latter. Limestones on the western slope are observed to the N of Mugodzhar Station—in the Sakpar-tyube height, where they border directly on the porphyries cropping out to the E; then they have considerable development along the Ak-tyken River (Aulie), and are, to a considerable extent, altered, thanks in part to contact with the igneous rocks that cut through them. Finally, they are also noticeable north of Mount Daudyn-tau. On the eastern slope they are observed to a considerable extent on Mount Alabas, near Mount Shuldak, then south of Mount Alabas—near the headwaters of the Kauldzhur River, near Ber-Chugur Station, and in many cuttings between Ber-Chugur and Karagandy stations. Conglomerates, sandstones, argillaceous and siliceous shales are observed more rarely—they were found both on the western and on the eastern slopes.

In addition, jaspers with a predominating red color are also observed. In some cases they occupy extensive areas, for example on the eastern slope of the Mugodzhar Mountains—to the E of Daudyn-tau. As their connection in some cases with Devonian siliceous shales shows, they represent Devonian deposits altered by the contact influence of igneous rocks.

In terms of their age, in the localities examined the Devonian deposits belong to two divisions of the Devonian: the Upper and the Middle. The Upper division could be observed at various points on the eastern slope. Thus, near Ber-Chugur Station one can see a considerable section of rocks, represented partly by conglomerates, partly by limestones with various fossils contained in them. Among the latter, goniatites play a visible role, namely representatives of the genus Tornoceras simplex Buch. In addition, Orthoceras sp., Spirifer tenticulum Vern., Spirifer Archiaci Murch., Cyrtia cf. Murchisoniana Vern., Rhynchonella pleurodon Phill., Rhynchonella reniformis Sow., Productus sp., and many others were found here. As can be seen, this fauna testifies to the existence here of the upper division of the Devonian system. The occurrence here of a goniatite fauna is—

is a new fact which supplements the observations made here by Venyukov. The latter, although he did find an Upper Devonian fauna not far from this point, near the headwaters of the Kaul-Dzhur River, did not encounter goniatites. He indicates the latter on the western slopes, near the Ak-Tyken-aul River. But there we did not find the bed with goniatites which he had encountered. Upper Devonian deposits were also observed near Mount Shuldak; here, on the right bank of the stream of the same name, above the volcanic rocks, one could see slabby gray limestones abundantly containing representatives of Spirifer Archiaci Murch. Finally, Upper Devonian deposits, represented partly by brownish-gray limestones and partly by marls and clays, were encountered in several railway cuttings situated between the Bert-Chugur and Karagandy stations. Thus, at the 500th verst of the railway, one can see in a cutting a section of a whole series of rocks consisting of thin- and thick-bedded brownish-gray limestones, alternating with brownish and brownish-gray, partly sandy clays. The dip of the beds is toward W or WWS at an angle of about 20°–30°. In these rocks Cyrtia Murchisoniana Vern. occurs in abundance. Similar rocks were also visible farther on (in the direction toward Karagandy) in the cuttings, their dip changing noticeably, which indicates the existence here of a series of small folds extending almost in a meridional direction.

The Middle Division was observed by us in part near Mount Alabas, but Upper Devonian forms were also observed there, although the fauna as a whole differs from the fauna of Ber-Chugur. Thus there are no goniatites here, but there are many remains of corals and Stromatopora, which of course indicates the reef character of the limestone. As Venyukov also pointed out, deposits of transitional character between the Middle and Upper Divisions of the Devonian are observed here. Mount Alabas represents part of a whole series of sections of Devonian rocks—limestone conglomerates and limestones—situated partly on the right and partly on the left bank of the Alabas River. The general dip of the beds is approximately toward O. Mount Alabas itself, situated on the left bank of the Alabas, is a rather broad ridge running approximately in a meridional direction and bounded on the east by a lowered area in which Carboniferous sandstones already crop out. In general, there is here a fairly considerable section of various beds, the fauna of which is quite diverse and must testify to the different ages of these beds. The study of the collected material can undoubtedly yield much in-

terrigenous. The Middle Devonian, apparently, is also present on the western slope of the Mugodzhar, namely at one point to the SW of the town of Airyuk—here sandstones and clay shales were encountered, among which a limestone interbed was found; in this interbed a Spirifer was found, which most likely belongs to Spirifer Anossofi, although without a detailed comparison of the form found I find it difficult to express myself categorically.

Devonian sandstones, conglomerates, and clay shales were observed both on the western slope of the Mugodzhar (to the SW of the town of Airyuk and to the NW of the town of Cheke-Karatau), and on the eastern slope (not far from the town of Alabas, to the SW of the latter). To the Devonian deposits should also belong, one must suppose, the siliceous shales and jaspers occurring partly immediately nearby, partly among the igneous rocks. This is indicated by their mutual relations with undoubtedly Devonian rocks, and also by their complete similarity to such rocks of the Urals.

Finally, the volcanic tuffs and porphyroids encountered there and here along the western slope of the Mugodzhar should belong to the Devonian.

Carboniferous deposits are represented in the Mugodzhar by, in places, grayish-brown sandstones and gray clays with plant remains, and in places by grayish-brown and grayish limestones with remains of marine fauna, not sharply displaced from a horizontal position. Both these and the other rocks alternate with one another. They form a meridional belt between Mount Alabas and Shuldak, filling a trough whose flanks are formed by Devonian deposits. This belt extends northward no farther than the parallel of Dauding-tau, and to the south it goes on for an indefinite distance, being masked there by later surficial deposits. In the limestones, alternating with sandstones, a rather varied fauna has been found, which, among other things, is distinguished by the almost complete absence of representatives of the genus Productus. In this fauna there are many representatives of lamellibranchs and gastropods, preserved, moreover, not especially satisfactorily, which, of course, makes an exact determination of the geological age difficult. It must be said, however, that alongside such poorly determinable forms, others have been found here which allow one to speak somewhat more definitely. Thus, alongside the indicated remains, at one locality were found Phillipsia cf. Derbyensis Mart., Orthotetes crenistria Phill., Spirifer cf. striatus Mart., Chonetes sp., and others (among the mollusks here Euomphalus, Bellerophon, Schizodus, and others occur more often); at another locality were encountered Brachymetopus sp., Orthoceras, Orthis resupinata Mart., and

one another, alongside frequently occurring representatives of the genus Euomphalus. This fauna has not yet been at all worked out, and therefore it is impossible to say precisely to which division of the Carboniferous system the deposits under consideration should be assigned. But their belonging to the Carboniferous system is beyond doubt—this is indicated by the general character of the fauna of the limestone interbeds and by their alternation with sandstones containing remains of Carboniferous flora. The latter is represented by numerous excellent impressions of the genera Lepidodendron and Sigillaria. The absence here of remains of ferns is noteworthy. Coal deposits are associated, among other things, with this belt of Carboniferous deposits several versts from the station Ber-Chugur. In view of the fact that a detailed, comprehensive study of this coal deposit was the subject of a special geological party under the direction of S. N. Nikitin, which was working there at the very same time as I was, I did not find it convenient in my investigations to deal with this point in detail; it should be noted that great hopes are placed on this deposit, all the more so because it lies not far from the line of the Orenburg–Tashkent Railway. The future will show how far these hopes may be justified.

B. Volcanic rocks.

Speaking of the volcanic rocks entering into the composition of the Mugodzhar, I must of necessity confine myself to the most general information, since the material collected has not yet been fully worked out.

The Mugodzhar include rather diverse volcanic rocks. They may be divided into several groups according to the type of magmas that served for their formation. Properly speaking, 4 magmas take part here: granitic, syenitic, dioritic, and diabasic.

To the granitic magma belong granites and quartz porphyries. Granites were encountered chiefly in the northern parts of the Mugodzhar—namely, east of the main ridge (Karatau), in the valley of the river Tashla-Or. Here a large area was found occupied by outcrops of micaceous granite of a brownish-yellow color. In some cases this granite is cut by veins of white quartz, and these veins sometimes attain considerable thickness. Often the quartz, weathering less strongly than the granite surrounding it, consequently rises above the surrounding locality in the form of more or less considerable hills, already from afar

striking the eye with their white color (for example, Mount Ak-Chuchak near the river Tashla-Or). Small outcrops of granite were also observed on the western slope of Dauding-tau.

Quartz porphyry is observed in the Mugodzhar Mountains at many points. It occurs almost exclusively in the form of veins cutting through various rocks: such cases were observed at many points in the southern, middle, and northern parts of the Mugodzhar. Veins of quartz porphyry cutting through more basic rocks—diabases and diabase porphyrites—could be observed in many cuttings along the railway between the stations Mugodzharskaya and Bert-Chogur; the same could also be observed on the pass across the Mugodzhar, somewhat south of the railway line, then near Mount Shuldak, near Mount Airyuk, Dauding-tau; veins of quartz porphyry also occur in the northern part of the Mugodzhar—to the south toward Mount Karatau, etc.

The syenite magma is represented by syenites and orthoclase porphyries. These rocks were observed east of Karatau, on Dauding-tau, in the vicinity of Mount Airyuk (orthoclase porphyries to the SW of this mountain), on Mount Shuldak, in the southern Mugodzhar, and elsewhere. The syenites apparently have especially considerable development on Shuldak.

The diorite magma is represented by diorites, which were observed in considerable elevations forming the more central parts of the Mugodzhar. Thus, diorites were found on Mount Airyuk, Dauding-tau, Shuldak, and also in the elevations lying to the O from Yaman-Urkach and the river Chilli, east of Karatau, etc.

The greatest significance among the volcanic rocks entering into the composition of the Mugodzhar belongs to representatives of the diabase magma—diabases and diabase porphyrites, as well as the amygdaloidal rocks associated with them. These rocks were found almost everywhere in the Mugodzhar. They were observed both in the foothills and in the main elevations forming the central chain. These rocks could be observed especially well along the railway line in the cuttings. The diabases here in many cases show a well-expressed spheroidal jointing. Moreover, these rocks are closely connected with the red jaspers; almost everywhere the latter were found, diabases were also observed. There are observations indicating that the jaspers formed from siliceous shales due to the contact influence of the diabases. Moreover, the fact must be noted that in some places the le—

Volcanic sediments upon diabase porphyrites, indicating a more ancient age of the porphyrites.

In connection with the diabase rocks there are also tuffs and porphyroids. These rocks were discovered at many points on the western slope of the Mugodzhar—south of the Mugodzhar station, and also north of the latter—along the Kunduzda River.

Among the rarer rocks one must note variolites, gabbro, and diallagic rocks. The first were discovered near the town of Airyuk and not far from the Bert-Chugur station, in the interval between the latter and Mugodzhar; at the latter locality the variolite is noteworthy in that it contains very large varioles. The second and third rocks were discovered southeast of the Mugodzhar station, and also in the northern part of the Mugodzhar—in the Cheke-Karatay Mountains.

The locality situated in the interval between the Mugodzhar and the Southern Urals.

The journey from Aktobe to Orsk made it possible to become acquainted with those rocks that make up the locality situated between the Southern Urals and the Mugodzhar. Here a whole series of rocks was discovered, beginning with the Permian and ending with the Devonian. The part of the road from Aktobe to the point where the road crosses the Yakshi-Kargaly River passes among Permian and Permo-Carboniferous rocks. The petrographic character of these rocks has already been indicated above. Farther on, the road runs almost across the strike through an enormous series of various siliceous shales, forming a broad meridional belt, thus almost as far as the very town of Orsk. Judging from the fact that among these siliceous shales, at some points, interbeds of limestones with Devonian fossils were found, they belong to the Devonian system. These shales are strongly dislocated, forming complex forms of folding. Their prevailing strike is NNW to SSO. Besides the siliceous shales, in the more eastern parts of the indicated area, closer to the town of Orsk, green and chloritic shales were encountered, and in one case also a hornblende schist.

Among these sedimentary rocks, igneous rocks were found at some points in the form of small outcrops—namely, diabase porphyrite (Yakshi-Kargaly River), diorite (hornblende and mica-hornblende—near the Igenda River), peridotite and serpentinite next to hornblende schists (also on the Igenda River, but only farther upstream). In general, however, it was necessary

one may note, in the indicated area, the rarity of outcrops of igneous rocks.

In addition to the rocks mentioned, at certain points in the area examined there were encountered small patches of Cretaceous glauconitic sands and friable sandstones containing remains of fish, Belemnitella mucronata Schl., and sponges, and thus belonging to the upper division of the Cretaceous system—the Senonian. These rocks were found near the Igendy River, where, among other things, they lie unconformably upon siliceous and hornblende schists, and also at several points farther on toward the town of Orsk.

Comparing the observations made here with what was observed in the Mugodzhar Mountains and in the area adjoining them from the west, one may conclude that the Mugodzhar Mountains are not a continuation of the area under consideration. Rather, one must think that they constitute a continuation of a more eastern part of the Ural Range, and that the belt connecting them with the Ural Range lies east of that through which we had occasion to travel.

Here, incidentally, a few words may be said about the time when the mountain-forming processes took place, as a result of which the Mugodzhar Mountains appeared and the rocks observed between them and the Urals were brought out of their horizontal position. As may be concluded from many established facts, the mountain-forming processes began already in Devonian time—this is attested by Devonian conglomerates, which in part were formed at the expense of those same Devonian rocks: evidently, the Devonian rocks were displaced from their original position and served as material for the formation of coastal deposits of the same Devonian time.

Mountain-forming processes also took place later, as is attested by the disturbed bedding of the Carboniferous, Permo-Carboniferous, and partly Permian deposits. Later, evidently, the mountain-forming processes subsided, since the Jurassic (?) and Cretaceous sediments occur almost horizontally, being bedded unconformably with the above-mentioned Paleozoic rocks where they were observed together. The most intensive emergence of various igneous rocks also coincided with the most intensive mountain-forming activity. This, judging from the available facts, occurred precisely in Devonian time.

Guberlin Mountains.

The excursion to the so-called Guberlin Mountains was limited to an examination of the locality: along the Chebakla River—from its mouth upstream to the settlement of Sary, along the road from the latter across the Koaldy River to the settlement of Khabarny, and from this latter along the highway to the settlement of Guberlinsky. This excursion made it possible to survey a considerable area of siliceous and clayey shales, with various volcanic rocks protruding among them. Among the latter, in the locality examined, peridotites and the serpentines associated with them are of great importance. Among the latter, moreover, much magnesite occurs. But, in addition, gabbro, diabase rocks, diorites, diabases, quartz porphyries, porphyrites, and others were observed here. During the excursion in the Guberlin Mountains we confined ourselves chiefly to collecting various rock specimens.

In addition to carrying out this task, we stopped to study one interesting point situated to the NNE of the settlement of Khabarny, 5 versts away. At this point a Carboniferous limestone crops out, forming small islands here. This limestone is interesting in that it contains an extraordinarily rich and varied fauna. The latter is of great interest. Containing many such typical representatives of the lower division of the Carboniferous system as Productus striatus Fisch and Pr. giganteus Mart., it at the same time includes a large number of diverse representatives of brachiopods, lamellibranchs, gastropods, and cephalopods. The study of this fauna could constitute a rewarding subject for an entire monograph. It is interesting that this fauna has a whole series of forms in common with the fauna of the Shartym limestone. And the diversity of this fauna once again confirms that the fauna of the lower division of the Carboniferous system of the Urals is distinguished by no less richness than the fauna of the upper division.

In conclusion I shall say a few words about the excursions to the village of Myachkovo and the village of Roiki on the Tom River.

The excursion to the village of Myachkovo, not far from Moscow, made it possible to collect considerable material from the Carboniferous limestones, which are distinguished by an abundance of organic remains. Along the way it was also possible to become acquainted with those sections that are present there in many quarries.

An excursion to the village of Roiki on the Tom River, undertaken by me jointly with P. A. Kazansky, made it possible to become acquainted with the Carboniferous deposits exposed near this village, containing a well-preserved marine fauna. In the abundance and variety of the latter, these deposits may be called classical. The collecting here of abundant paleontological material is of all the greater interest because the Carboniferous deposits of Siberia have as yet been studied very little, and their study should, of course, begin with the examination of the most classical localities.

In presenting this brief preliminary report, I am fully aware of its incompleteness. But a more complete report can be presented only after a detailed working up of the collected material, and this will, of course, require a considerable amount of time.

In conclusion, I consider it my moral duty to offer to the Council of the Tomsk Technological Institute my sincere gratitude for the assistance in carrying out my excursion which it rendered me by providing the necessary funds for it.

Prof. M. Yanishevsky.

Tomsk,
13 December 1904.