i834.j ROCK STREAMS. not 



pass from one simile to another. We may imagine that 

 streams of white lava had flowed from many parts of the 

 mountains into the lower country, and that when solidified 

 they had been rent by some enormous convulsion into 

 myriads of fragments. The expression ''streams of 

 stones," which immediately occurred to every one, conveys 

 the same idea. These scenes are on the spot rendered 

 more striking by the contrast of the low, rounded forms of 

 the neighbouring hills. 



I was interested by finding on the highest peak of one 

 range (about seven hundred feet above the sea) a great 

 arched fragment, lying on its convex side, or back down- 

 wards. Must we believe that it was fairly pitched up in 

 the air, and thus turned ? Or, with more probability, that 

 there existed formerly a part of the same range more 

 elevated than the point on which this monument of a great 

 convulsion of nature now lies. As the fragments in the 

 valleys are neither rounded nor the crevices filled up with 

 sand, we must infer that the period of violence was subse- 

 quent to the land having been raised above the waters of 

 the sea. In a transverse section within these valleys, the 

 bottom is nearly level, or rises but very little towards either 

 side. Hence the fragments appear to have travelled from 

 the head of the valley ; but in reality it seems more probable 

 that they have been hurled down from the nearest slopes ; 

 and that since, by a vibratory movement of overwhelming 

 force,* the fragments have been levelled into one continuous 

 sheet. If during the earthquake t which in 1835 overthrew 

 Concepclon, in Chile, it was thought wonderful that small 

 bodies should have been pitched a few inches from the 

 ground, what must we say to a movement which has 

 caused fragments many tons in weight, to move onwards 

 like so much sand on a vibrating board, and find their 

 level ? I have seen, in the Cordillera of the Andes, the 

 evident marks where stupendous mountains have been 

 broken into pieces like so much thin crust, and the strata 

 thrown on their vertical edges ; but never did any scene, 



* "Nous n'avons pas ^te moins sainiii d'itonncment 4 la vfle de I'lnnom- 

 brable quantity de pierres de toutcs grandeurs, boulcverBdcs Ics uiics sur Ics 

 autrcs, et ccpcndant ranj;ie9, comme si dies avoient iti amonccliics nigli- 

 gfemmcnt pour rcmi»lir den ravins. On ne se Uussoit pas d'admirer les effeU 

 prodigicux de la nature," — Pemety, p. 526. 



t An inhabitant of Mendoza, and hence well capable of judjfinK, assured 

 •np that, during the several years he had resided on these isl.ind^, hi- had 



V er felt the ahghtest shock of'^an earthquake. 



