A HISTORY OF CUMBERLAND 
PROTEROZOIC PERIOD 
Stturtan Rocks. 
B. Kirkby Moor Flags. 
Bannisdale Slates. 
Coniston Grits and Flags. 
A. Pale Slates. 
Graptolitic Mudstones. 
Unconformity. 
Orpovician Rocks. 
B. Bala Volcanic and other Rocks. 
A. Borrowdale Volcanic Series and Milburn Rocks. 
Upper part of the Skiddaw Slates. 
Camprian Rocks. 
Lower part of the Skiddaw Slates. 
I. Tue Sxippaw States.—(a2) The geological records of Cumber- 
land date back to an early period in the history of the earth, long prior to 
the existence of any mountain, valley, or coast feature now to be seen, and 
also long before any but the very simplest forms of animal or plant life 
now existing on the earth had come into being. The evidence from 
which we can draw any safe conclusions regarding the events which 
occurred in the earlier chapters of the historical geology of Cumberland 
is, as might be expected, very fragmentary and imperfect, and not a few 
of the known facts are capable of more interpretations than one. Still 
after a careful and prolonged search, carried on by many patient in- 
vestigators in this field of study, a sufficient number of facts has been 
brought to light to warrant us in drawing a few conclusions with a 
tolerable amount of certainty. We do know that the earliest records 
of Cumberland are by no means the oldest even in Britain ; but, omitting 
any further reference to these areas outside the county, we may begin by 
considering the facts presented by the vast pile of slates, mudstones, and 
grits, which form the upland area lying to the east and the south-west of 
Bassenthwaite, and which includes Grassmoor, Saddleback, and Skiddaw 
(or Skidda). To these, the most ancient rocks of Cumberland, the name 
Skiddaw Slates is usually applied. Internal evidence supplied by these 
rocks makes it quite clear that they are the broken, much-disturbed, and 
greatly-altered, representatives of what was at one time a vast pile of 
marine sediments, representing the mud, sand and shingle brought down 
to adelta by a large river draining a great tract of land some distance 
away. Every particle of these old rocks represents what was formerly 
part of some older solid rock constituting that land, and its present 
position is due entirely to the prolonged action of rain and rivers upon 
that old land surface. The evidence further assures us that the area now 
occupied by Cumberland was in those remote times being gradually 
lowered by earth movements, which proceeded at a very slow rate, and 
which, on the whole, kept pace with the deposition of the sediment. 
Occasionally a somewhat less slow subsidence than usual brought about 
a greater depth of water ; while at other times the sediments forming 
the old delta pushed seaward a little faster than the subsidence carried 
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