TJie Lower Carboniferous Rocks of Cumberland. 525 



Lonsdaleia floriformis, and this fossil is still more characteristic 

 north of Cockermouth, indicating that this species entered the 

 Carboniferous seas from the west, arriving much earlier here than 

 in the North-AVest Province. 



With regard to the lowest beds exposed in the Egremont area, 

 I collected from the Longlands (east) spoil-heap an alga closely 

 resembling Girvanella externally, but identified by Professor Garwood 

 as Spongiostroma round a central nucleus of Mitcheldeania. By 

 analogy ^^'ith the North- West Province, this should indicate the base 

 of Sj. Apart from the evidence afforded by this isolated specimen, 

 I agree with Mr. Edmonds that the lowest horizon developed in the 

 area is the Nematophyllum minus subzone (S>) — a particularly 

 fine development of the bed being seen in the spoil-heap at the 

 Winscales mine, where the iron ore is won from the limestone through 

 a capping of 950 feet of drift, St. Bees' Sandstone, and Brockram. 



The Nematophjlhim minus subzone is, in fact, the lowest zone 

 definitely recognized anywhere between Penrith and Egremont, 

 though there are indications that the Michelinia zone (C2) was once 

 exposed at Dacre (Penrith). It is probable, from a consideration of 

 the radial dip (which is little more than sufficient to carry beds of 

 Dj age over the present summit of Carrock Fell) and of the faulting, 

 that beds of D^ age once enveloped the whole Lake District massif, 

 though it is remarkable that, with the single exception of the outlier 

 at Wilton Fell (Egremont) — of 83 age — no relic has yet been 

 discovered of this former Carboniferous mantle. 



There would apjjear to be a rapid thinning out of the lower zones 

 between the Dalton-in-Furness area, where all the horizons from the 

 Athyris glahristria zone upwards are developed, and the Egremont 

 area 20 miles to the north, and it would be an interesting study, if 

 possible, to trace this thinning out by means of borings through the 

 superficial Triassic deposits. 



No true basal conglomerate, nor any Polygenetic Conglomerate 

 occur at the base of the limestone in the Egremont area, the lime- 

 stone resting directly across the edges of the Skiddaw slates. The 

 Polygenetic Conglomerate is, however, well exposed at Woodhall 

 (Cockermouth), Uldale (Caldbeck), and Holghyll (Penruddock). 

 Its irregularity in distribution, thickness, etc., and its high angle of 

 dip, in marked unconformity with the gently dipping limestones 

 above, lead to the conclusion that it was no part of the Carboniferous 

 submergence j^roper ; considering, however, the vast amount of 

 erosion necessary to produce the constituent material since SUurian 

 times, and the mclusion of fragments of Shap igneous rocks, it is 

 probable that it was formed as a continental deposit of Upper Old 

 Red Sandstone age, a conclusion reached by other writers on the 

 subject. 



The other features brought out by mapping the limestones between 

 Cockermouth and Penrith are chiefly concerned with local variations 

 in the faunal assemblages, though generally speaking the subzones 



