LOFTUS — TURKO-PERSIAN FRONTIER. 317 



stone, into the heart of the great chain of Ala Dagh, which forms the 

 watershed between the waters of the Murad Chai and the streams 

 which flow into the Lake of Van. The bed of the ravine is 

 strewed with small volcanic pebbles, among which obsidian is not 

 uncommon. 



At rather more than midway up the ravine the travertin rocks 

 cease, being forced through by a series of finely-grained granitic and 

 trappean rocks, frequently capped by basalt. On the ascent of the 

 lofty pass of iVla Dagh are numerous lavas, and at the summit is a 

 very beautiful pink variety, unobserved elsewhere. 



In the commencement of the descent of the ravine of the Ardish 

 Chai, conducting to the Lake of Van, we have again many volcanic 

 rocks, among which may be noticed a peculiar heavy grey rock, 

 enclosing small crystals of quartz, mica, &c., and several varieties of 

 basalt, sometimes columnar, &c. Further down the ravine beds of 

 travertinous limestone make their appearance. At about eleven 

 miles from the foot of the pass is another hot spring, having a tem- 

 perature of 165° Fahr., in fact near that of boiling water. The water 

 is strongly chalybeate and slightly saline ; the calcareous deposit 

 from it is reddened by the presence of iron. The same peculiarity 

 exists here as at other springs depositing travertin, i.e. there are 

 older deposits of similar nature in the immediate neighbourhood, 

 though at this peculiar locality they are not of great extent. From 

 this point, however, in the descent are frequent patches of a yellow 

 tufaceous limestone, overflowed by columnar basalt. Near Khoch 

 Kiipri, where the ravine begins to open out into the plain of Ardish, 

 at the junction of a large stream from the N.W. with the Ardish 

 Chai, a flow of amorphous basalt occurs, apparently derived from 

 the east ; it is slightly amygdaloidal, the vesicles containing car- 

 bonate of lime. Disseminated through the mass are numerous flat 

 crystals of a transparent white mineral. Beyond this commences 

 the soil of the plain, which consists of a light volcanic yellow sand, 

 producing rich crops of wheat. About two miles further, a short 

 descent over the same amorphous basalt conducts to the alluvial 

 plain of the river at Irishat. The basalt abuts against the western 

 extremity of a low range of white limestone, containing volcanic 

 crystals. From beneath the basalt there issues the large stream 

 which flows into the Lake of Van on the east of Ardish. 



The Lake of Van. 



It is not generally known that a remarkable rise has of late years 

 taken place in the water of the Lake of Van ; and, as this phaenome- 

 non comes under the consideration of the geologist, I give here the 

 results of my observations and inquiries on the subject. 



Mr. Layard, in his second work, "Discoveries in the Ruins of 

 Nineveh and Babylon," p. 408, has briefly alluded to this phse- 

 nomenon. 



The Lake of Van was carefully surveyed by Lieut. Glascott, R.N., 

 in August 1838, when travelling in company with Mr. Brant, 

 H.B.M.'s Consul at Erzerum, and the result was given to the public 



