40 THE SALMON RIVERS OF SCOTLAND 



which were associated with the cruive. Since the year mentioned^ 

 therefore, the criticism as to the destructive action of the cruive has 

 been removed, and as the flow through the cruive-box is of easy 

 gradient, fish experience no difficulty in making the ascent. 



EIVER FOETH. 



The Forth is formed by two head streams, the Duchray Water 

 and the Avondhu, which rise barely three miles from one another 

 and unite a mile west of " the clachan of Aberfoyle." Each branch 

 rises at a very high altitude, and each is remarkable for the rapidity 

 with which a quite low level is reached. The denudation of this 

 region has been extreme. Ben Lomond is 3192 feet, and the source 

 of the Duchray is about the 3000 feet level on the north side of the 

 mountain, and only about a mile and three-quarters from the shores 

 of Loch Lomond. The course of this stream is so broken by falls 

 that it is not possible for salmon to ascend. The length of its 

 channel is only 13f miles, and the junction is only 80 feet above 

 sea-level. The Avondhu, i.e. the black water, rises at an altitude 

 of about 1900 feet, and after 9 miles of rapid descent passes into 

 Loch Chon, a mile and three-quarters long and 290 feet above sea- 

 level. Continuing its descent, it next enters Loch Ard, two miles 

 and a quarter long and 103 feet above the sea, from which Aberfoyle 

 is not far distant. 



The great, low, transverse valley which stretches across Scotland 

 between Forth and Clyde has its ill-defined divide running also 

 in a transverse direction for a considerable distance, as will be seen 

 by reference to the watershed map, south of the Forth, and the 

 insignificant tributary, Kelty tributary. It is a flat alluvial region 

 in which a river can make but little headway, and hence the Forth 

 in working to the eastward describes the most extraordinary succes- 

 sion of windings. It has 18 J miles to go to Stirling and only 80 

 feet of a fall. The result is that with its many "links" or 

 " crooks " it actually travels 39 miles. There is much sameness in 

 the course, each part looking very much like the other, yet this 

 expanse of flat country and varied woodland, with the mountainous 

 region of the Trossachs in the distance has a charm of its own, and, 

 when well lit, conveys a splendid sense of space and freedom ; a 

 landscape that looks best with great white clouds in a high sky. It 

 is through this flat expanse from below Stirling to Loch Lomond 

 that the proposed ship canal across Scotland is planned out. 



As a salmon fishing river the Forth above the junction with the 



