542 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
becoming finally very rough in a narrowing valley down to its 
junction with the South Branch, 950 feet above the sea. At the 
junction the South Branch is much the larger stream, perhaps 
twice as large, and runs in a distinct valley of its own against a 
plateau wall on the south. Evidently it is the main stream, while 
the North Branch enters by a newer valley, the upper part of 
which may originally have entered the Clearwater valley by a 
route suggested by the map. 
Below the junction the enlarged river runs in a somewhat 
deep winding valley, with occasional ledges on one side or the 
other, and a bouldery bed of much drop. Such is it down to the 
Clearwater, 717 feet above the sea. This stream is not a fourth 
the size of the main river, shoal, warm and very clear. The main 
river itself has now become surprisingly large, carrying even at 
lowest summer level an ample amount of water for canoeing. 
But throughout the length of Sevogle, canoeing would be next 
to impossible because of its shallowness, roughness and incessant 
fall. 
Below the Clearwater the Sevogle continues of much the same 
character as above, though with everything upon a large scale, 
except the height of the valley walls. These gradually fall off 
until they do not exceed 100 feet in height, though the valley 
walls, sometimes forming great cliffs, still continue steep, form- 
ing a sharp edge with the plateau. The valley is always drift- 
bottomed, and clearly all pre-glacial in age. Two miles below 
Clearwater occurs a great bend of the river to the eastward, a 
bend which represents one of those great turns so characteristic 
of all the old Northumbrian rivers, as I have earlier shown 
(Note 93). Then it keeps the same general character down 
well-nigh to Sheephouse Brook, when there appears on the north 
bank a grand semicircle line of great cliffs, at the end of which 
the valley suddenly narrows to a typical short post-glacial gorge 
(the Narrows), with extinct fall. I could not determine the 
position of the pre-glacial channel, which I suspect is on the 
north bank behind the line of cliffs. Half a mile below the Nar- 
rows comes in Big, or Sheephouse, Brook, a very long stream with 
apparently a post-glacial mouth. A little below is Little Sheep- 
house Brook ; three miles up this stream is said to occur a fine fall 
