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gradual that it can only be detected by comparing the thicknesses 
of these rocks at points widely separated. Each bed of limestone, 
as a rule, is based upon a bed of sandstone, which often bears a 
coal seam, and the limestone, in its turn, is almost invariably 
succeeded by more or less shale. In the eastern part of the district 
these drifted materials are thicker than they are to the west; the 
proportion being four or more of sediment to one of limestone on 
the east, three of sediment to one of limestone on the western side 
of the Eden, while as the rocks are traced round the north side of 
the Lake District towards the Whitehaven area the Yoredale 
sediments, as Mr. J. D. Kendall pointed out some years ago 
(and was well known long previously to those who mapped the 
district, Mr. Colvin, Mr. Ward, and the author), gradually become 
thinner and thinner, until eventually we reach a point where the 
limestones of the Yoredale Series, from the Great, Main, or Twelve 
Fadom Limestone, downward, have nearly coalesced into one 
undivided mass of limestone. The top of the Lower Yoredales is 
thus made to appear as the top of the Mountain Limestone; 
which, however, is almost entirely absent in North-West Cumber- 
land. The very same feature is observable in the very same beds 
in the eastern part of the Craven area. The obvious explan- 
ation in both cases is that the areas where the limestones were 
deposited without intermixture with materials of sedimentary origin 
were, all through the period they represent, areas of clear water. 
How that fact is compatible with the existence of islands and 
mountains, etc., on the same spot must be left to others to 
explain. 
The normal succession of the Yoredale Rocks is as follows; 
the highest beds being stated first, and the local names given in 
square brackets :— 
Millstone Grit, with several coals of workable thickness and 
quality. 
Yoredale Rocks. (1) Upper Section :— 
Thickness about 500 feet, beds very persistent everywhere, and not 
subject to the westerly thinning that affects the sedimentary beds 
belonging to the Lower Section :— 
