SmuTimiNc ok the Mountains. 
Jill 
sand ; but it is difficult to realise from a casual glance 
the vast amount of material that is thus brought 
down to lower levels. If we would trace the sediment 
to its source, we must seek it among the rocks of the 
mountains far away. Step by step, we may tract', it 
up along the higher courses of the river, them along 
mountain streams rushing over their rocky beds, 
tumbling in cascades over broken rocks, or leaping in 
waterfalls over high projections of rock, until we 
come to the deep furrows on the sides of mountains, 
along which loose fragments of rock come tumbling 
down with the cascades of water that run along 
these steep channels after heavy rain, leaving at 
the base of the mountain great fan-shaped heaps of 
b tones. 
* Oft both slopo and hill uro torn, 
Whore wintry torrontu down have borno, 
And hoapod upon tho cum bo rod land 
ItH wreck of gravel, rooks and sand.’ 
“Those accumulations are gradually carried away 
by the larger mountain streams, which, in hurrying 
them along, cause a vast amount of wear and tear ; so 
that their corners are worn oil', and they get further 
and further reduced in size, becoming mere round 
pebbles lining the bed of the stream, and linally, by 
the time they roach the large slow-moving rivers of 
tho plains, are mainly reduced to tiny specks of mud 
or grains of sand. So, then, the rivers and streams 
not only transport sediment, but they manufacture it 
as they go along; and thus they may he considered as 
