446 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and is chiefly made up of a dark coloured coarse slate or flagstone, 

 through which are distributed rounded concretions, (sometimes 

 spoiling the slate,) in which, as well as in the colour and bedding 

 of the rock, in the presence of small calcareous veins, and the ap- 

 pearance of a great bedded mass of ripple marked flagstones with- 

 out slaty cleavage at the top of the group, there is seen a near 

 resemblance to the Denbigh flags. In the upper flags just alluded 

 to, there are also (in the gill above Hawkshead Fould) calcareous 

 masses and lenticular beds of limestone not fossiliferous, and pro- 

 bably not continuous, and therefore not considered by the author 

 as forming a second band of limestone. 



The Coniston flags thus characterised extend from the extre- 

 mity of Shap Fell to the top of the Duddon Estuary, and might 

 readily be laid down on a good map. It only remains, therefore, 

 to determine their relative position from the included fossils. 



In the Brathay quarries were found Graptolites ludensis in 

 considerable abundance, and at another locality, within a few hun- 

 dred feet of the Coniston limestone, Atrypa compressa was also 

 plentiful, and was accompanied by a Creseis. At Cold Well, con- 

 siderably above the Brathay quarry, appeared Asaphus caudatus ; 

 and at Kent-mere in the same group Astrea ananas, Creseis being 

 distributed throughout. All these fossils occur in the Wenlock 

 shale, or Lower Denbigh flag. The author therefore concludes that 

 the series in question represents the Lower Denbigh flagstones, 

 and is the equivalent of the Wenlock shale. 



3. Coniston or Furness Grits. This name is given to a group 

 of bluish grey grits of great thickness, and very highly in- 

 clined, overlying the Coniston flags. It is on the whole a well 

 defined group ; but at its N.E. end is broken up by the interpolation 

 of slaty bands, and loses its well defined mineral type. It may, how- 

 ever, be distinctly traced, and laid down on a map, from Bannisdale 

 Head to Broughton ; occupying a zone, on the average, more than 

 half a mile wide. No fossils have as yet been discovered in it, 

 but the author brings it into comparison with some hard grits 

 which alternate with the lower Denbigh flags, north of the Holy- 

 head road ; he does this however only for the purpose of exhibiting 

 analogies of structure in rocks of nearly the same epoch. 



4. Ireleth Slates, Sf-c. This is described as a great group possess- 

 ing a considerable unity of character, and characterised by rocks 

 with a good slaty cleavage distinct from the bedding, the slates 

 being sometimes good enough for quarrying, and alternating with 

 gritty bands, some of them very coarse, and rarely passing into a 

 conglomerate form. The beds of this group are greatly contorted 

 through their whole range, and especially at their north-eastern 

 and south-western ends, and the thickness of the whole is very 

 difficult to determine justly. For convenience of description, the 

 whole series is separated by the author into three divisions, 

 namely : — 



a. The Lower Ireleth slates, a band of considerable width, made 

 up of beds dipping at high angles, and steadily to the S. E. Being 



