GEOLOGICAL SOCIETY OF LONDON. 
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very like that of Coniston, dipping east 40°, of which onl}^ about 
a thickness of twelve feet is laid open ; and at Turtle-bank 
Heights, south-west of Blawith, where it has been quarried near 
the top of the south-east face of the hill, and is a dark gray 
limestone, twenty feet thick, striking north-east and dipping 
perpendicularly ; from this spot it runs by Cockin^s-hill to the 
side of Coniston Water, half a mile north of Water Gate. The 
fossils found by Mr. Marshall in this bed near Blawith were 
identified as Lower Silurian species. 
5th. Flagstones and Slates of Kikrby Ireleth. — These are placed 
by Professor Sedgwick below the Blawith limestone. No. 4, but 
as Mr. Sharpe considers, erroneously : nevertheless, although no 
fossils have been found in them, he considers them to be the 
uppermost bed of the Lower Silurian series, because they are 
always conformable to the undoubted Lower Silurian beds below 
them, and are not equally conformable to the beds above. As 
this southern edge forms the boundary line of the Lower Silurian 
formation, Mr. Sharp traced them carefully along their whole 
course, from their first appearance rising from under the moun- 
tain limestone, on the east of Ireleth, till they are hidden by 
the old red sandstone of Birkbec-beck. Near Ireleth it is only 
used for building stone, but at Kirkby Ireleth are quarries ex- 
tending for a mile and a half along the range of the bed, supply- 
dark-blue slates of very good quality. At Horse Spital Quarry 
the beds dip south-east 80°, and the cleavage dips south-east 55°, 
both sets of planes striking north-east : this coincidence in the 
strike of the bedding and cleavage planes is common in all this 
district ; yet at Lord Quarry, close to the last-mentioned, the 
beds dip N.N.E. 20°, while the cleavage dips S.SE. 70°. Fur- 
ther east the rock is of inferior quality, and is rarely worked for 
roofing slate : its usual course is north-east passing by Suberth- 
waite, Blawith, Nibthwaite, at the foot of Coniston Water, where 
much building stone has been quarried, and the rock is well ex- 
posed, being a dark-blue flagstone streaked with gray : between 
