Yol. 62.] ANNIVERSARY ADDRESS OP THE PRESIDENT. XCvii 



that the most remote source lies far east of this, but the feeder which 

 comes from the east runs in a synclinal fold, whereas the waters 

 which run into the Birkbeck at Shap Wells rise on the axis of an 

 anticline. Here they run at first over Carboniferous rocks, and not 

 until the Birkbeck approaches Tebay does it enter the Silurian tract, 

 in which, as already stated, it continues to near Kirkby Lonsdale. 



The geographical source of the Lune is at a height below 

 1000 feet, whereas the tract of Howgill Fells through which 

 passes the gorge of the Lune (which is a continuation of the 

 Birkbeck valley), has a much greater elevation. A little south of 

 Tebay we have a fell in Grayrigg Forest rising to a height of 

 1619 feet above sea-level, at a distance somewhat more than a mile 

 west of the Lune, and Uldale Head having a height of 1553 feet 

 about the same distance east of the river. Anyone standing on 

 Shap Summit will be at once impressed by the great mass of 

 Silurian fells on the south, with the general level far above that at 

 which he is located, and will note the sudden change from the wide 

 valley above Tebay to the gorge south of that place. The relation- 

 ship of the river to the general slopes and to the strata is illustrated 

 in the accompanying section (fig. 5, p. xcviii). 



The Shap-Summit anticline is the eastern portion of the spoon- 

 shaped Lake-District uplift ; and the Birkbeck stream, therefore, is 

 one of the streams belonging to the radial drainage. At the time 

 of its initiation the mass of the Howgill Fells cannot have stood 

 in the way, unless we suppose that the newer rocks on which the 

 drainage was initiated varied so greatly in thickness between 

 Shap Summit and the top of the Howgill Fells as to allow 

 of a continuous downward slope, over which the river could 

 flow — an extremely unlikely supposition, considering the short 

 distance (less than 10 miles) which separates them. The more 

 likely explanation is that the upper waters of the Lune were first 

 initiated, and that subsequently the uplift of the Howgill and 

 adjoining tracts took place with sufficient slowness to permit of the 

 river (an antecedent stream) keeping its course open, thus modifying 

 the drainage of the western end of the subsidiary dome. I have 

 made this suggestion elsewhere, but it has been adversely criticized, 

 and as I had not then stated all the facts I set them forth here. 



One other modification in this tract must be noticed, namely, the 

 general southward flow of the waters of the Eawthey towards 

 Sedbergh. This river, as the result of the lowering of the Lune 

 Yalley, probably cut its way back, along the line of weakness 



