on Trias and Carboniferous in the Caucasus. 561 



The discovery by Messrs. Wittenburg and Robinson of these 

 Werfen Beds in the Caucasus emphasizes the importance of the 

 Caucasian Trias as a connecting-link between the Trias of the Alps 

 and the Himalaya, for beds of this period have long been known 

 to occur at Julfa in the Araxes Valley (which separates Russian 

 Armenia from Persia), containing Meekoceras and species of Pseudo- 

 monotis, which Bonnet (Bull. Soc. Geol. France, ser. 4, xii, 312) 

 has shown to be allied to those of the Hede^istroemia beds of the 

 Himalaya. The upper, unfossiliferous part of the Julfa Series, 

 consisting of 200 metres of marly limestones overlain by 1,000 

 metres of black limestones and dolomites, is probably equivalent to 

 the Middle and Upper Trias of the Caucasus. 



Still more recently W. N. Robinson (op. cit.) in 1912 was able 

 to establish the fact that the Triassic beds of the Caucasus overlie 

 Upper Carboniferous limestones, as at Julfa. The locality is also 

 in the basin of the Bielaya River, at Mt. Gepho on the left bank 

 of the River Kisha (Choga), a right tributary of the Bielaya. 

 Mt. Gepho rises to a height of 1,200 feet above the Tegen stream, 

 which flows into the Kisha, and the natural section discloses the 

 following downward succession : — 



1. Trias {Ladinian). — (1) Grey, arenaceous flagstones with plant- 

 remains and badly preserved fossils (not specified). Similar sand- 

 stones (dipping 70° N.E.) occur on the western spur of the Pshekish 

 ridge. To the north-east the sandstones are dark red, very micaceous, 

 and attain a considerable thickness. 



(2) Conglomerate of small pebbles, mostly of quartz, but it varies 

 considerably in thickness and materials ; it extends nearly to the 

 summit of Mt. Gepho and dips west. This conglomerate uncon- 

 formably overlies the Carboniferous Limestone and is greatly 

 developed along the northern slope of the Caucasus in the Kuban 

 district. To the north-west it crops out in the Bielaya Valley, 

 a little above Khamyshki (Alexievsk), and to the south-east as far 

 as the Urups River and the upper course of the Zelenguk. Between 

 the Bielaya and the Little Laba the conglomerate forms a large 

 anticline and composes the ridges Pshekish and Bambak and the 

 southern slope of the Mastakan ridge ; it occurs also on the south- 

 west side of the Dudugush ridge towards Mt. Oshten. 



2. Upper Carboniferous. — (1) Grey limestones, forming rocky cliffs 

 on both sides of the Tegen defile. They are so compact that the dip 

 is scarcely visible, but in one place it seems to be southerly. They 

 contain a rich Brachiopod fauna, e.g. Entetes contractus, Gemm., 

 E. carniolicus, Schellw., Uncinulm velifer, Gemm., Reticularia lineata, 

 Mart., Chonetes uralica^ Moll., Notothyris exilis, Gemm., RichtJiofenia 

 lawrenciana^ de Kon., Aulosteges, Geyerella, with Pelecypods, Gastro- 

 pods, and sponges belonging to the families Sphaerospongidse {Ketero- 

 coelia) and Sphserocoelidse {Sollasia, Steinmannia). 



(2) Black, argillaceous slates, forming the bed of the Tegen River, 

 with intercalated, thinly laminated, black sandstones, dipping rather 

 steeply to the south. They are extensively developed to the south- 

 west, south, and south-east of Mt. Gepho, towards the main axis of 

 the Caucasus. No fossils occur in the slates ; but the interbedded 



DECADE V. — VOL. X. — NO. XII. 36 



