Scientijic Intelligence. — Hydrography. 193 



rare occurrence had taken place and caused considerable sensa- 

 tion. On the morning of the 25th August 1832, an enormous 

 avalanche descended suddenly from the mountain of Kasbek in- 

 to a valley, through which the military road from Tiflis passes, 

 and covered it for a distance of two wersts in length. The 

 mass of snow extended across the entire ravine, which has a 

 breadth of forty fathoms, and its thickness amounted to about 

 forty faden (fathoms), so that the communication was interrupt- 

 ed by about a million and a half cubic fathoms of snow, ice, 

 and masses of rock rolled down by the avalanche from above. 

 The river Terek, which flows through the ravine, had its course 

 so completely blocked up, that it burst through its banks at 

 the upper end of the defile, tore away several bridges, destroyed 

 a part of the road, and flooded the lower parts of the country, 

 before it formed a new passage for itself. The inhabitants were 

 saved by their own sagacity and their thorough acquaintance 

 with the mountains, foi* 6ven a week before the avalanche was 

 precipitated, they had remarked signs which indicated with cer- 

 tainty the approaching catastrophe, and had accordingly remov- 

 ed to a considerable distance with their herds and moveable pro- 

 perty. The forerunners of a great and dangerous avalanche are 

 more or less frequent small avalanches of snow and loose earth 

 from the Kasbeck, a mountain which rises to the height of 2500 

 toises above the level of the Black Sea. When the yearly aug- 

 menting masses of snow which lie on this mountain and its de- 

 clivities, are increased to such an extent as to lose the power of 

 coherence, they slide gradually downwards, carrying along with 

 them large masses of rock, and giving rise to a thundering noise. 

 It is at the same time remarked, that the mountain tributary 

 streams of the Terek become considerably swollen and bring down 

 earth and stones. As the Kasbek is seventeen wersts distant 

 from the place where the avalanches are precipitated into the 

 ravine, some time must necessarily elapse before the descending 

 snow accumulates to such an extent as to roll over all Uie pro- 

 jecting cliff's which give protection to the road, and it is easy for 

 the mountaineers to take to fligrht before the danger reaches 

 them. Only two similar avalanches are known to have taken 

 place in Grusia since it belonged to Russia; of which one hap- 

 pened in the year 1808, and the other in 1817; and notwith- 



VOL. XV. NO. XXIX. — JDLY 1833. N 



