412 



PHYSICAL GEOGRAPHY. 



the year 1248, and exhibits marks of the disruption in its present appearance, which has 

 been sketched by Mr. Bakewell, to whose Travels in the Tarentuise we are indebted for 

 most of the particulars concerning the event. The ruins of the mountain entirely buried 

 five parishes, -with the town and church of St. Andre, spreading over an extent of about 

 nine square miles. These ruins are now called les Abymes de Mi/ans; and, notwithstanding 

 the lapse of many centuries, and the presence of numerous vineyards which have since 

 been planted, they present in many places a singular and impressive scene of desolation. 

 A favourable view of the fall, at a safe distance, was afforded by the locality, for Mont 

 Grenier is almost isolated, advancing into a broad plain, which extends to the valley of 

 the Isere. It is several miles in length, but very narrow, and attains the height of 4000 

 feet above the plain, being an abutment of the mountains of the Grand Chartreux. The 

 summit is capped with an immense mass of limestone strata, not less than six hundred feet 

 in thickness, presenting on every side the appearance of a wall. The strata dip gently to 

 the side which fell into the plain. This mass of limestone rests on a foundation of inollase. 

 a term applied by the Genevese to the softer beds of sandstone, and underneath this, 

 strata of limestone alternate with it. There can be little doubt that the disruption was 

 occasioned by the gradual erosion of the soft strata, which undermined the mass of 

 limestone above, and projected it into the plain. The part that fell had probably been for 

 some time nearly detached from the mountain by a shrinking of the southern side, where 

 there is at present a large rent, upwards of 2000 feet deep, which seems to have cut off a 

 section, that 



" Hangs in doubtful ruins o'er its base," 



and threatens a renewal of the event of 1248. The projected portions forming the 

 Abymes des Myans exhibit a series of small conical hills, varying in height from twenty 

 to thirty feet, composed of fragments of calcareous strata, precipitated to the distance of 

 two and three miles from the mountain. Falling from the upper bed of limestone with 

 which Mont Grenier is capped, the velocity they would acquire by descending from so 

 great a height, making due allowance for the resistance of the atmosphere, Mr. Bakewell 

 estimates at not less than three hundred feet a second. The projectile force gained by 

 striking against the base of the mountain, or against each other, has spread them over 

 the plain ; where, in the course of years, the rains and currents of water from dissolving 

 snows have washed away the loose earth, and furrowed channels, giving to the masses of 

 stone the aspect they now present, that of detached conical hills. The chronicles which 

 have preserved a record of this occurrence do not state whether the fall of the mountain 

 was preceded by any forewarnings that allowed to the inhabitants the opportunity to 

 escape. Certain it is that the town of St. Andre, then a place of some importance, being the 

 ancient seat of the deanery of Savoy, and other parishes, were so entirely overwhelmed, 

 arid to such a vast depth, that nothing has ever been discovered belonging to them except 

 a small bronze statue. It has been calculated that the quantity of matter that fell, would 

 be more than four hundred millions of tons in weight, occasioning a shock inconceivably 

 awful, being precipitated from the height of three quarters of a mile into the plain. The 

 dislodged material stopped a little short of the church at Myans, dedicated to the Virgin, 

 and called Notre Dame des Myans. Hence the church acquired celebrity, and pilgrimages 

 are made to its shrine by the Savoyards, to whom it would be heresy to intimate, that the 

 elevation of the ground assisted the efforts of the Virgin in arresting the calamity. 



The sudden descent of masses from mountains, whether of rock and earth, or snow and 

 ice, in the form of an ordinary Alpine avalanche, has frequently propagated a series of 

 striking and destructive changes. Choking up to a certain height a contracted valley, and 

 arresting the progress of its stream, the formation of a lake ensues, which becomes per 

 manent if the barrier is composed of solid materials in a quantity sufficient to resist the 



