1897.] NATURAL SCIENCES OF PHILADELPHIA. 419 



cut is about 400 ft. long with two sigmoid curves. One hundred and 

 fifty feet from tbe northeast end a very much decomposed grayish 

 layer occurs containing Garnets, some of them flattened on the planes 

 of bedding. About 75 ft. from the northeast extremity a mass of 

 white quartz occupies a large space and penetrates to the surface 

 of the cut above, embedded in the mica schist. Another mass of 

 white quartz strikes across the railway, south 20° west, mica schists 

 follow this to the end of the cutting. 



The next object of study was the Bolchoi Taganai (or Great 

 Taganai). There are three mountains called Taganai, viz: Bolchoi 

 (or great), Sredny (or medium) and Maly (or small) north of Sla- 

 tooust, which are connected together and with the Oural-Taou or main 

 chain and water-divide by high plateaux. They are separated from 

 the north flank of Kossotour by the valley of the river Bolchaia- 

 Tessma. 



All of these heights are composed similarly of a quartzite summit 

 overlying a friable sandstone with kaolinized Feldspar, and this 

 latter resting on garnetiferous mica schist with subordinated lime- 

 stones. The dips being to the north-west, faults with a southeast 

 hade repeat this succession, three times, the easternmost repetition, 

 being the lowest but the most extensively developed and formed by 

 the chain Oural-Taou. On the east side the heights are abrupt 

 precipices, but on the west they are gently inclined and accessible. 



The river Kiolim, which traverses the Ourals and forms part of the 

 Siberian river system, descends this divide to the north, the river 

 Tessma an affluent of the Si, taking its course to the south, 

 where it ultimately joins the waters of the Caspian Sea. At the 

 base of the Bolchoi-Taganai (called Otkliknoi) occur outcrops of 

 diabases. The words of M. Tschernischew are herewith repeated. 

 " The detailed study of our section demonstrates that all the Taganais 

 show the same succession of rocks rent by a series of faults. It is 

 equally beyond doubt that the quartzites of the Taganais correspond 

 completely with the quartzites and sandstones of the lower Devonic that 

 we have already encountered on our trip to the mines of Bakal and 

 environs. It results indubitably that the metamorphic rocks which 

 support the quartzites of the Taganais are the same clastic modified 

 rocks of the lower Devonic developed in the more western parts of the 

 Ourals." 



A study was made of the but little altered Devonic measures near 

 the works of Koussinsk where there is an outcrop of dolomitic lime- 



