Basin of the Eden and north-western Coasts of Cumberland, ^c. 385 



The direction of the south-western boundary has been ascertained much 

 more correctly, by observations carried on from one end of it to the other. 

 Its minute description is, however, thrown into an appendix, being necessarily 

 made up of details, which, though tiresome and uninstructive if read before 

 the Society, may assist in the completion of our geological maps, and be of 

 some value as matters of reference. Such facts only will be mentioned here, 

 as throw light on the structure of the red sandstone, and help to establish its 

 subdivisions. 



Where the red sandstone series first appears in the ramifications of the 

 Eden, near Brough and Kirkby Stephen, it is chiefly seen as a conglomerate, 

 abounding in fragments of mountain limestone, and cannot, when it has that 

 form, be mineralogically distinguished from the overlying conglomerates on 

 the skirts of the Mendip Hills. It is generally in a state of complete indu- 

 ration where the calcareous fragments abound ; and it sometimes passes into 

 mere brecciated beds of limestone : but other parts, especially where the peb- 

 bles are rounded, and the sand and cement abundant, are soft and crumbling. 

 In the arrangement of the several varieties of the formations, though the 

 beds are nearly horizontal, there is very little approach to symmetry or order. 

 Hence the conglomerates offer a very unequal resistance to the action of the 

 elements ; and above Kirkby Stephen, where the Eden makes its way through 

 them, they have been worn into channels of extraordinary complexity. Chasms 

 and deep basins are naturally scooped out where the rock offers the least re- 

 sistance ; and by these inequalities great eddies are formed in the river during 

 every mountain flood, which by whirling round the hard pebbles at the bottom 

 of each basin, gradually grind away the solid rock, and carry on the work of 

 excavation far below the surface. Caverns are thus formed ; and masses of 

 conglomerate become so far undermined, as sometimes to allow a new passage 

 to the river far below the level where it once flowed. 



A fine example of this kind occurs at Stenkreth Bridge near Kirkby Stephen, 

 where the waters, after washing the inclined strata of mountain limestone be- 

 low Pendragon Castle, plunge among the horizontal masses of conglomerate ; 

 after which, for a short space, they are heard roaring in a subterranean chan- 

 nel, communicating by a narrow cleft (called the span of the Eden) with what 



by mountain torrents. Further towards the north the calcareous chain declines in elevation, and 

 the demarcation of the new red sandstone is often ill defined. The best approximation to its course 

 that has yet been published, may be seen in Mr. Greenough's map. It passes (as there represented) 

 to the east of Brampton, after which it ranges, in a sinuous line, very much concealed by alluvial 

 detritus, but on the whole bearing nearly due north till it crosses the Liddel and enters Scotland ; 

 then it is deflected nearly to the west, and crosses the Esic just above Canobie Bridge. 



