STATEMENT BY MR MARSH. 227 



hillock which he climbed before he entered the gorge, the structure 

 aud composition of which conclusively show that it must have been 

 washed out of this latter by torrential action, will often account 

 satisfactorily for the disposal of most of the matter which once filled 

 the ravine, 



" When a torrent escapes from the latei'al confinement of its moun- 

 tain walls and pours out of the gorge, it spreads and divides itself 

 into numerous smaller sti-eams, which shoot out from the mouth of 

 the ravine as from a centre, in diff"erent directions, like the ribs of a 

 fan from the pivot, each carrying with it its quota of stones and 

 gravel. The plain below the point of issue from the mountain is 

 rapidly raised by newly-formed torrents, the elevation depending on 

 the inclination of the bed and the form and weight of the matter 

 transported. Every flood both increases the height of this central 

 point and extends the entire circumference of the deposit, 



" Other things being equal, the transporting power of the water is 

 greatest where its flow is most rapid. This is usually in the direction 

 of the axis of the ravine. The stream retaining most nearly this 

 direction moves with the greatest momentum, and consequently 

 transports the solid matter with which it is charged to the greatest 

 distance. 



" The untra veiled reader will comprehend this the better when he 

 is informed that the southern slope of the Alps generally rises suddenly 

 out of the plain, with no intervening hill to break the abruptness of 

 the transition, except those consisting of comparatively small heaps 

 of its own debris brought down by ancient glaciers or i-ecent torrents. 

 The torrents do not wind down valleys gradually widening to the 

 rivers or the sea, but leap at once from the flanks of the mountains 

 upon the plains below. This arrangement of surfaces naturally 

 facilitates the formation of vast deposits at their points of emergence, 

 and the centre of the accumulation in the case of very small torrents 

 is not unfrequently a hundred feet high, and sometimes very much 

 more. 



" The deposits of the torrent which has scooped out the Nautzen 

 Thai, a couple of miles below Brieg in the Valais, have built up a 

 semicircular hillock, which most travellers by the Simplon route pass 

 over without even noticing it, though it is little inferior in dimensions 

 to the great cones of dejection described by Blanqui. The principal 

 course of the torrent having been — I know not whether spontaneously 

 or artificially — directed towards the west, the eastern part of the hill 

 has been gradually brought under cultivation, and there are many 



