Geological Society. 501 



adaptation of the structure of the Ichthyosaurus to the habits of the 

 animal. 



A communication was afterwards made " On the coal fields on the 

 north-we>tern coast of Cumberland, &c., &c. : " by the Rev. Pro- 

 fessor Sedgwick, M.A., F.R.S., F.G.S., and Williamson Peile, Esq., 

 of Whitehaven, F.G.S. 



Ill a former paper* the authors described the range of the carboni- 

 ferous limestone from the neighbourhood of Kirkby Stephen to 

 Egremont; and showed that the formation admitted of two divi- 

 sions : the lower representing the scar limestone of the Yorkshire 

 sections, the upper (also like the Yorkshire sections) exhibiting 

 alternations of limestone, sandstone, and shale, w th thin seams of 

 coal. They commenced with a short notice of rocks and sections 

 made through this upper division, which in its range towards the 

 western coast of Cumberland, appears gradually to thin off, and lose 

 its importance. They then proceeded to describe in more detail, 

 and with many illustrative sections, a still higher coal field ; which 

 is on the same parallel with the great Northumberland and Durham 

 coal-fields, and in the quantity of carbonii'erous beds subordinate to 

 it, is in no resptct inferior to them. 



This field is bounded by the red sandstone of St. Bees Head ; by 

 the carboniferous limestone, in a part of its range above described; 

 by the sea coast between St. Bees Head and Maryport; and by the 

 new red sandstone in its ran^^e from Maryport to Chalk Beck near 

 Rosley. The whole system appears to thin off near Rosley, and is 

 succeeded by some sterile, alternating, masses of red shale and sand- 

 stone, to which the miners, though improperly, have given the name 

 of the " great red metal dyke." To the east o'i this series of red beds 

 the rich upper coal-field never appears to have extended. From 

 many borings and workings near Whitehaven, it is inferred that the 

 upper division of this carboniferous limestone, as well as the millstone 

 grit, have almost disappeared ; and that the coal measures are 

 brought nearly into immediate contact with the lower division of the 

 limestone. In some places the whole limestone has thinned off, and 

 the coal measures seem to rest almost immediately on the Skiddaw 

 slate. 



The authors commence their details, in the present paper, with an 

 account of the Whitehaven coal-field, which they separate into three 

 divisions : the southern, or How-Gill colliery ; the middle, or Town 

 field bounded by a great downcast d3l<e towards the north ; and the 

 northern, or Whin-Gill colliery, bounded by an anticlinal line which 

 enters the sea near Parton. The strata found in these several parts 

 of the field are described by the help of the sinkings and borings of 

 Croft Pit, and by o.lier sii. kings in various parts of the field down to 

 the limestone. A comparison is then made between this series of 

 strata and those exhibited in corresponding sections of the Harring- 

 ton and Workington fields ; and it is shown that the whole series 

 may he conveniently separated into two divisions : the upper, con. 

 taining two princi[)al bands of coal, called the " lUnnKKk Bund," and 



♦ Proceedings {IcdI. Soc, vol. ii. p. PJS. 



