152 J. EH. Marr—Drainage of the English Lakes. 
rise to a ridge along the present line of watershed of the Lake 
District, but along the centre of the anticline, though there may 
have been higher ridges of older rock existing to the north of the 
'Skiddaw axis, which determined the trend of the pre-Carboniferous 
valleys, and that this was the case is indicated by an examination 
of the mode of occurrence of the irregular patches of the basal 
Carboniferous conglomerate, and a study of their included pebbles. 
These conglomerates, from their extremely local distribution, are 
generally and probably rightly supposed to have been deposited in 
the troughs of inequalities, though there is some doubt as to the 
region from which the material was brought. Mr. Clifton Ward, in 
the paper cited, comments upon the close similarity between the 
pebbles of the Mell Fell conglomerate to the rocks forming the 
Ludlow beds of the Kendal district, and the great rarity of local 
rocks in the conglomerate. I have recently detected a pebble in 
the same conglomerate at Roman Fell near Appleby, containing 
a fossil which appears to be Rhynchonella nucula, a characteristic 
Ludlow form. But, that these pebbles came from the south is 
unlikely for the reason to be noted immediately, and similar rocks 
occur in the southern uplands of Scotland on the south side of what 
probably constituted a pre-Carboniferous mountain axis, so that the 
drainage may well have come from this direction. Prof. Hughes 
has detected in the same conglomerates in the Lune Valley, pebbles 
of the well-known Keisley limestone of Appleby, a peculiar and 
easily recognizable rock, which is developed in this form in no other 
part of the district, and which, for reasons which cannot be here 
given, is unlikely to occur elsewhere. This discovery indicates a 
drainage on the pre-Carboniferous slopes in a southerly direction, 
and suggests a northern source for the pebbles of the conglomerate. 
Now Keisley is separated from the Lune Valley by a continuation 
of the main watershed of the Lake District, so that at the time of 
the formation of the conglomerate, if the pebbles of the Lune Valley 
have actually come from Keisley, the present watershed did not exist, 
and indeed the way in which the Carboniferous rocks rise from 
Tebay to Shap Wells, and then sink to the Eden Valley, proves that 
this elevation was post-Carboniferous. 
Recent discoveries, it will be seen, fully confirm Mr. Hopkins’s 
conclusion that the Carboniferous rocks were laid down over the 
area of the present Lake District upon an even horizontal surface. 
§ 3.—Post-Carboniferous Changes. Formation of the Dome, and 
Determination of the Drainage. 
The examination of the area has shown, what would be a priori 
expected, that the pre-Carboniferous drainage was not determined 
by the more modern Lower Paleozoic rocks of the district, and these 
could be converted into the highest ground of the region by no 
other means than a further upthrust, which took place in post- 
Carboniferous times. Even then, the drainage would not radiate 
from an area of Lower Paleozoic rocks, unless these rose above the 
surrounding high ground caused by the accumulation of the up- 
