Geological Society. 229 



strict, described by Dr. Berger, and by Dr. Buckland and Mr. Cony- 

 beare in the third volume of the first series of the Geological Society's 

 Transactions. 



After alluding to the labours of these celebrated observers, the au- 

 thor defines the extent and physical features of the district described 

 in his memoir. He states that it is bounded on the west bv the es- 

 carpment of tjie chalk from Kenbaan Head to Corky; on the south 

 by a line drawn from that place to Genon Point ; and on the east 

 and north by the Irish Sea. The area, thus circumscribed, is tra- 

 versed in a N.W. direction by the Aura mountains, from the southern 

 part of which several, long, projecting ridges with flat, broad sum- 

 mits and precipitous sides, branch off ; and in the northern part of 

 the district the surface is occupied by detached hills, having a direc- 

 tion parallel to that of the main chain. The height of the principal 

 mountains varies from one thousand to two thousand feet. Their 

 eastern declivity is abrupt, but their western is formed by a succes- 

 sion of undulating hills, which gradually descend into the low country 

 extending from Kenbaan Head to Corky. 



The principal formations described, are mica-slate, porphyry, old red 

 sandstone, carboniferous limestone, coal measures, new red sand- 

 stone and conglomerate, lias, mulatto or green sand, chalk, and 

 trap. 



May 1 6. — A paper " On the Geological Relations of the stratified 

 and unstratified Groups of Rocks composing the Cumbrian Moun- 

 tains," by the Rev. Adam Sedgwick, V.P.G.S. F.R.S. Woodwardian 

 Professor in the University of Cambridge, was read. 



Chap. I. — Introduction. 



The author first shows, that the limits of the region to be described, 

 are defined by a zone of carboniferous limestone, based here and 

 there upon masses of old red conglomerate. This zone is described 

 as entirely unconformable to the central system, and for the phaeno- 

 mena presented at the junction of the two great classes of rocks, he 

 refers to previous memoirs read before the Society. 



The rocks of the central system are separated into stratified and 

 unstratified; and the stratified are divided into four distinct groups, 

 in the following descending order : 



1 . Greywacke and greywacke-slate ; the whole group based on 

 beds of limestone and calcareous slate, and bounded at its upper 

 surface by a part of the carboniferous zone. 



2. A great formation of quartzose, chloritic, roofing slate and fel- 

 spar porphyry; alternating in great, irregular, tabular masses, each 

 passing into, or replacing, the other; the whole having nearly a 

 constant strike, and dip similar to that of the preceding group. 



.3. Skiddaw slate — a very fine, dark, glossy clay-slate, occasionally 

 penetrated by quartz veins, sometimes passing into a coarse grey- 

 wacke and grcywacke-slate. 



4. Crystalline slates between the preceding group and the cen- 

 tral granite of Skiddaw Forest. 



It is then shown, that the mineralogical axis of the whole region 

 may be i)Iaced in the direction of a line drawn from the centre of 

 Skdiduw Forest to Egremont, and that on the north side of this line 



