OS a a 
129 
the north, and are succeeded in that direction (i.e. as we approach 
Roman Fell summit) by a thick series of ashy shales, ashy sand- 
stones, tuffs, and lavas, having an aggregate thickness of at least 
1100 feet. For this series, including the fossiliferous beds, the 
lecturer proposed the name of the Helton Moor Series. Their 
highest beds are not seen; but independent evidence, admitted 
on all hands, shews that these beds are older than the rhyolitic 
tuffs of the Seat, on Helton Fell. These latter are known to be 
identical with the tuffs of Knock Pike and Dufton Pike. Above 
these last comes the true Coniston Limestone series, which is seen 
in detached faulted blocks at Helton Smelt Mill, Keisley, Pusgill, 
Swindale Beck, Melmerby, &c.; and as a nearly continuous band 
extending from Shap Wells southwestward past the head of Winder- 
mere, Coniston, to Furness. It is seen again in and around the 
higher waters of the Rawtha, on the east side of the Howgill Fells. 
The Coniston Limestone series as a whole is of marine origin (like 
the older Helton Moor Shales), and it may be regarded as a series 
of fossiliferous calcareous shales in which calcareous matter pre- 
dominates on different horizons in different localities. So that a 
bed of limestone in one locality may be represented by a bed of 
calcareous shale at a second locality not far off. The lecturer 
regarded the well-known and very fossiliferous limestone of Keisley 
as simply a less-argillaceous representative of the limestone seen in 
the higher part of the Coniston Limestone series in Swindale Beck, 
above the village of Knock. The existence of a thin calcareous 
band full of fossils in the volcanic rocks near the head of the river 
Sprint, midway between Shap Wells and the head of Windermere, 
has long been known; but the actual existence of any limestones 
near this geological horizon outside the Lake District was not 
recognized until the Helton Moor series was discovered by the 
lecturer in 1878. Beds of lava, tuff, trass, and flows of felspathic 
mud occur in connection with both the Coniston Limestone and 
the Helton Moor series. It is just possible that the remarkable 
series of fossiliferous beds discovered by Mr. J. E. Marr at Dry 
Gill in the Caldbeck Fells, may be the equivalent in time of the 
9 
