316 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



crater of the celebrated Skaptar Yokul in Iceland! If to these 

 streams be added those of Suphan Dagh, on the north shore of the 

 Lake of Van, separated from Kharpanak by only thirteen miles, we 

 have an infinitely greater volume of melted matter flowing from the 

 three craters of this region than has, I believe, proceeded from any 

 known volcanic source. 



In the direction of Dyadin to the N.W., numerous little peaks or 

 "tepehs" of red and blue marls project their heads from the plain, 

 having their bases surrounded by the lava-flood ; they are in fact 

 islands in a basaltic sea. 



At the miserable Kurd village of Kundii, seven miles from Bayazid, 

 a low range of blue marls commences, and bears towards the N.W., 

 having its S. W. base overflowed by the lava from Tendiirli. The 

 road continues for 4^ miles along the skirt of this range, over a 

 quantity of rough scorise. At one locality, just before quitting this 

 marl range, I observed a patch of brownish-blue trap-rock, contain- 

 ing olivine and amygdaloidal cavities filled vdth carbonate of lime, 

 overflowing the marls. 



The piled and confused mass of scorise which forms the eastern 

 termination of the basaltic streams from Tendurli, has much the 

 aspect of the terminal morain of some immense glacier. From 

 beneath the N.W. side of Tendurli a red marl range, which passes 

 to the east of Dyadin, first shows itself, overflowed by the basalt. 

 A short pass over this range conducts to the basin of the Miirad 

 Cha'i (Euphrates). Near the summit, but below the basalt, is much 

 brown fine-grained lava. 



From the village of Daoud (near which is a warm sulphur-spring) 

 the Castle of Dyadin is seen, six miles distant, standing on a high 

 basaltic clifl* on the right bank of the Miirad Chai. 



Immediately on quitting Daoud, a patch of loose white chalk-soil 

 is passed ; this further on changes to a bright-yellow volcanic tuff, 

 containing much pumice and leucite. 



A low pass of lava intervenes before descending to the main 

 stream of the river. A somewhat compact black lava, with analcime 

 and leucite, forms the top of the pass ; this rests on a light-pink 

 variety, with the same minerals. A thick bed of the above-described 

 yellow tuff succeeds ; and the base of the section consists of the 

 same pink lava which occurs immediately above. 



On the left bank of the river, at a short distance upon the left of 

 the road, is a hot sulphur-spring, 1 34° Fahr. The water bubbles up 

 with great \4olence from a small hole, and, in flowing out of a small 

 natural basin, leaves a yellowish calcareous deposit, similar to that 

 observed in other travertin-springs, but much less in quantity. It 

 has a slight odour of sulphur, and is nauseous to the stomach, though 

 tasteless. There are likewise several smaller springs in the same lo- 

 cality, having various different temperatures. The rocks around are 

 of yellow travertin, having much resemblance to the deposit from the 

 spring, but frequently compact and altered to a grey slaty limestone. 



From this point the road follows up the west branch of the river, 

 through high cliffs of cream-coloured and grey travertinous lime- 



