534 Geological Society: Mr. D. Sharpe on the 



having enabled him to correct some errors committed on his first 

 examination, and to extend his observations into Lancashire. 



On both occasions Mr. Sharpe took for his base-line the bed of 

 Coniston limestone described by Professor Sedgwick*, being con- 

 vinced that Mr. Marshall has rightly considered that limestone as the 

 lowest bed of the Silurian system in this districtf, and in all his 

 descriptions he adheres to the ascending order. 



1st. Coniston Limestone. — It is doubtful whether this bed is 

 continuous at its western extremity, or occurs only in detached 

 patches. The two western portions of limestone at Water Blain 

 and Low House are a mile and a quarter south of the bearing of the 

 line of the bed east of the latter place, but are exactly on a line 

 with the strike of the bed beyond Coniston ; a great fault between 

 Low House and Greystone House being counterbalanced by the 

 whole of the smaller faults between that spot and Coniston, which 

 are pointed out in Professor Sedgwick's memoir. Mr. Sharpe gives 

 a list of fossils collected in this bed and the shales above it at Torver 

 Fell, Coniston, Long Sleddale, &c, in which are several of the spe- 

 cies of Orthis, Spirifer, and Leptana, found by Mr. Murchison in 

 the Lower Silurian deposits, and several undescribed species. 



2nd. Slates, Shales, and Flagstones. — These are well exposed on 

 Torver Fell, where the following series may be seen: — 



a. Brown shale. 



b. Dark blue slate of good quality ; the beds dip E.S.E. 40°, and 

 the cleavage dips S.S.E. 80°; it contains many fossils, much com- 

 pressed and distorted, nevertheless a few Lower Silurian shells are 

 made out. 



c. Indurated brown shale. 



d. Blue flagstone rock, a bed well known in the district, and 

 mentioned by Professor Sedgwick and Mr. Marshall ; at Torver, 

 where it gives good roofing-slate as well as flags, the beds dip 

 south-east 45°, and the cleavage south-east 80°. To the eastward 

 of Windermere this bed and the lower bed of slate b run together, 

 and the whole of the Lower Silurian formation diminishes in thick- 

 ness. 



e. Indurated shale. 



/. Shear Bed, which supplies brownish-blue flags, taken along the 

 bedding of the rocks, which is free from slaty cleavage. 



This series of slates, flagstones, and shales, may be traced above 

 the Coniston limestone from the Dudden to Shap Fells, although 

 the separate beds cannot always be distinguished. 



3rd. Grey Slaty Grits, described in Mr. Sharpe's former paper 

 as the " Lower division of the Windermere rocks," but now classed 

 as part of the Lower Silurian formation ; they consist of a great 

 thickness of hard gritty grauwacke, variously affected by cleavage, 

 and may be traced from the Dudden, below Broughton, to Shap 

 Fell. 



4th. Blawitk Limestone, "the second band of calcareous slate" 



• Geol. Trans. Second Series, vol. iv. p. 47- 



f Report of the British Association, 1839, Sections, p. 67. 



