304 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



position, and the production of the Plain of Selmas, probably by 

 the eruption of the hornblendic rocks on the north and south. 



2. The denudation of the edges of the upraised rocks, and the depo- 



sition of the horizontal thin bed of coarse gravel. 



3. The formation of a vast bed of travertin from thermal springs. 



4. The eruption of the felspathic mass, carrying with it portions of 



travertin, torn from the deposit in situ, and contorted during 

 instantaneous elevation. 



5. The overflow of the basaltic coulee from the west or north-west, 



covering up and altering the edges of the vertical sandstones 

 and contorted travertin ; and the cooling of the heated mass, 

 whereby probably was formed the fault or crevice through 

 which the Chehrik stream flows. 



6. The deposition of the alluvial soil of the Plain of Selmas. 



7. The present action of the thermal springs, depositing powerful 



beds of travertin ; which action must have been constant since 

 the end of the second period above alluded to. 



Section from Selmas to Giiverjin Kalah, on the Lake of TJrumia^ 

 via Issi Su. Fig. 1 7. 



On quitting the Plain of Selmas, the road traverses an open pass 

 at the village of Ali-abad, between Zendesht Dagh (an extension of 

 Anjiilukh Dagh), on the west, and the peak of Siiret Burni (so 

 called from the sculptured equestrian figures of the Sassanian 

 dynasty), on the east. The rocks here consist of blue, altered, and 

 crystalline limestone, much contorted. A little further on, to the 

 left of the road, there rises from the plain a solitary peak, the sum- 

 mit of which is of the same blue limestone, passing downwards into 

 a heavier compact variety, filled with small transparent crystals of 

 carbonate of lime, which give it the aspect of a calcareous grit. 

 This is underlaid by hard, fine-grained, red, compact fluor, asso- 

 ciated with red jasper. The jasper reposes on a mass of pink, 

 quartzy, granitic rock. The above-mentioned deposits here dip 

 towards the north, as they likewise do on the south side of Zendesht 

 Dagh, at the base of which is the hot sulphur-spring of Issi Su. 

 This spring rises from beneath a mass of altered blue limestone, sur- 

 mounting grey limestone-breccia, which emits a strong odour of 

 sulphur ; both of these rocks have been thrown off from the side 

 of the range. The temperature of the spring is 99° 5' Fahr. It 

 deposits a considerable efflorescence of carbonate of soda, generally 

 pure white, but frequently tinged with yellow and red, from the 

 presence of oxide of iron. In the same neighbourhood, at a place 

 called Temtemah, there is a cold spring depositing travertin, which 

 I omitted visiting. 



From Issi Sii, the road crosses a considerable spur running in an 

 easterly direction from the main chain. It is composed of pink 

 quartzy rock, — pink felspathic granite, — a highly micaceous dark gra- 

 nite, — compact hornblende-rock, — and various hornblendic mixtures. 



A gradual descent conducts to the small plain of Kiirt Keran, 

 containing numerous villages. 



