112 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 7, 



Dalton), on the other side of the estuary of the Duddon. The 

 rocks are there in a vertical position ; and, crossing from the shore 

 of the Duddon estuary towards Dalton, we have the following se- 

 quence : — 



(1.) Sharp ridges of porphyry and schaalstein (exactly like those 

 under the Conistoii limestone). 



(2.) Beds of dolomite, broken and shattered, with Favosites 

 fibrosa (but fossils extremely rare). 



(3.) Calcareous slate, with many fossils of the Coniston lime- 

 stone. 



4.) Thin bands of schaalstein, slate and porphyry. 



1^5.) Obscure bands of vertical slate, ill-exposed, and with no 

 well-defined fossils. 



Taking the mineral structure and fossils into account, I had no 

 hesitation, during my preceding visit in 1844, to class a part of this 

 calcareous mass with the Coniston limestone. From the great thick- 

 ness of the shattered dolomitized limestone, I was disposed to think 

 it probably a mass of mountain limestone (for that formation is close 

 at hand) entangled among the porphyries. I now feel assured that 

 it is only an altered form of Coniston limestone, and its thickness is 

 perhaps not greater than that of the same limestone on the Cumber- 

 land side of the Duddon estuary. Let it be borne in mind that there 

 is the enormous dislocation already alluded to, and that we have in 

 this very district the indications of great but anomalous eruptions of 

 contemporaneous porphyry both immediately before and after the 

 formation of the Coniston limestone, and all difficulty will, I think, 

 vanish. With the exception of the dislocated mass above described, 

 there are no Lower Silurian rocks to the south of Duddon Bridge. 

 The statements in the abstract of my former paper amply define the 

 general age of the Coniston limestone, and enable us to class it 

 with the highest portions of Caradoc sandstone. 



2. Coniston fi,ags. — Respecting this group I have not many details 

 to add to those of my former paper. It forms the true base of the 

 Upper Silurian rock of this part of England. I have now traced it 

 through parts of the valleys of Dent, Sedbergh, and Ravenstone 

 Dale, on the eastern skirts of the fossiliferous slates, and in several 

 places it contains Cardiola interrvpta, along with the Upper Silurian 

 fossils ( Graptolites Ivdensis, &c.), mentioned in the abstract of my 

 paper of last March. There can therefore be no doubt about its 

 true place in the series. Among the highest beds of this group on 

 the road between Hawkshead and Coniston are Orthoceratites sub- 

 undulatus, Portlock, and another species not yet described. 



3. Coniston grit. — The beds of this group, consisting of hard 

 grits, &c., have a remarkably uniform character, considered as a 

 whole, — only at their northern end they are degenerate so as to 

 give a less impress to the features of the country. They reappear 

 in the great undulations of Howgill Fells and Middleton Fells, &c. 

 Throughout they show a remarkable association with spherical con- 

 cretions often more or less calcareous, in which respect they offer 

 analogies with many of the harder Upper Silurian grits of North 



