71 



mere Rocks." Another bed of limestone, that of Blawith, which 

 Mr. Marshall had also shoAvn to contain organic remains of the 

 Lower Silurian type, is stated by Mr. Sharjje to underlie the Ireleth 

 flags and slates ; and he considers all this series, fi?om the Coniston 

 Lower limestone upwards, to form the representative of the Lower 

 Silurian rocks, in which the Kirkby Ireleth slates are included; not 

 from any fossils they contain (none having been found in them), 

 but because they are strongly affected by a slaty cleavage, and though 

 invariably conformable to the other Lower Silurian beds, are not 

 equally conformable to those above them. After tracing the de- 

 marcation of these slates, Mr. Sharpe then adverts to the fine deve- 

 lopment of the Lower Silurian rocks in High Furness (Lancashire), 

 where the formation has a north-easterly and south-westerly strike, in 

 perfect parallelism with the I'idges and valleys, which direction is 

 strongly contrasted with the outline of the same rocks in West- 

 moreland and among the lakes, where the valleys are in the line of 

 extensive faults, transverse to the strike ; and it is in this region 

 of greater disturbance that the rocks are in the most crystalline state 

 (slaty cleavage, &c.). The Windermere rocks having been deprived, 

 as above stated, of their lower member", by the admission of our au- 

 thor, and having been found to contain a species of Orthoceratite 

 unknown in the Lower Silurian rocks, it is I think now more than 

 ever probable* that they represent the Wenlock shale of the Silu- 

 rian region ; the more so as, resting on a great thickness of admitted 

 Lower Silurian rocks, they are surmounted by unequivocal Lower 

 Ludlow rock. In working out the exact relations of the Ludlow 

 rocks of Westmoreland to those of Shropshire and Siluria, Mr. 

 Shai'pe has very considerably added to his memoir of last year, both 

 by the addition of many species, and by distinguishing the Upper 

 from the Lower Ludlow rock by fossils peculiar to each ; and from 

 what I know of the value of the Terehratula navicula as a guide, I 

 completely approve of the arrangement, by which all the strata con- 

 taining that shell are considered to be Lower Ludlow rocks. 



It is indeed very remarkable, that a tract containing so little cal- 

 careous matter as the neighbourhood of Kendal, where the Lower 

 and Upper Ludlow rocks, including in the latter the red tilestones, 

 are strikingly displayed, should have afforded so many as eighty 

 species of fossils Avhich are identical with those published from the 

 same formations in the Silurian region. Having myself visited this 

 tract for the second time, and since Mr. Sharpe completed his last 

 survey, I am sure he will unite with me in expressing the great 

 obligations of all southern geologists like ourselves to the indefati- 

 gable industry and quick eye of Mr. John Ruthven of Kendal, who 

 is the great purveyor of fossils both from the Silurian and Carbonife- 

 x'ous rocks of the neighbourhood of his native place, and who, con- 

 tributing largely to the Museum of Kendal, so ably directed by two 

 gentlemen of that town f, is acquiring for himself a reputation in the 

 North scarcely inferior to that which has been assigned to Miss 



* See Discourse of last year. f Mr. Gough and Mi\ Danby, 



