806 THE GEOGRAPHICAL SIGNIFICANCE OF FLOODS, 



are commonly located at rut-convergencies and immediately 

 below local barriers or hardnesses such as rocks and tree-roots. 

 Portions only of these gutters may consist of trenches such as 

 those just described, nevertheless, where they occur, the smaller 

 side-streams near the amphitheatrical heads are " hungup " over 

 the main rut. 



2 Incipient Canon-Contours. — These interesting geographical 

 features represent the more advanced stages of road-gutter, or 

 similar valley, making. Very frequently they occur in decom- 



Fig.4. — Incipient canon formed by flood-waters at Uralla (New Eng- 

 land). Note the double slope in the canon. The lower valley showing basin, 

 spurless walls, and U -shape in section marks the work of a very heavy 

 storm. The upper portion of canon shows ordinary spur-development. 

 The lower contour shows a remarkable resemblance to glacial forms. 



posed rock-masses, and tley may, in a few decades, attain 

 depths as great as 50 feet. They also afford striking examples 

 of V-shaped valle^^s possessing well-marked overlapping spurs. 

 Their origin, in New England, can be usually traced to the 



