134: Geological Society. 



PROCEEDINGS OF LEARNED SOCIEITIES. 



GEOLOGICAL SOCIETY. 



March 14th, 1917.— Dr. A. Smith Woodward, F.R.S., 

 Vice-President, in the Chair. 



Tlie following communication was read : — 



' The Carboniferous Limestone bordering the Leicestershire 

 Coalfield.' By Leonard Miles Parsons, D.I.C., B.Sc, F.G.S. 



The inliers of Carboniferous Limestone situated along the 

 northern border of the Leicestershire Coalfield crop out in two 

 well-defined series : — a Western series composed of almost hori- 

 zontal beds exposed by stream-erosion, and an Eastern series in 

 ■which the limestone is highly inclined and complicated by faulting. 

 The thinly-bedded limestones, shales, and dolomites of the 

 W^estern inliei-s are of a slightly-higher horizon than that of 

 the upj^ermost beds of the more massive dolomites seen at Breedon 

 and Breedon Cloud farther eastwards. In no part of the distinct 

 is the base of the Carboniferous seen, although borings have 

 shown that the limestone rests upon pre-Cambrian rocks in the 

 neighbourhood of Charnwood Forest. 



The dolomites of the area yield evidence of two distinct periods 

 of dolomitization — one pre-Triassic, the other subsequent to the 

 Trias. During the former period the bulk of the rock was" 

 dolomitized. 



The fauna of the limestones and dolomites indicates the presence 

 of palseontological horizons ranging fi'om D^ to Dj^I^s inclusive. 

 The D, portion of the sequence, consisting of thickly-bedded 

 dolomites without chert, contains a fauna similar to that of 

 the Caldon-Low facies of the south-western part of the Main 

 Midland Province, the. rare species Productus humerosus being 

 found at Breedon and Breedon Cloud. 



L'nlike the rocks of the D, subzone of Derbyshire, the corre- 

 sponding beds in Leieestershii'e contain no igneous rocks equivalent 

 to the ' Toadstones.' Higher dolomites with chert, equivalent to 

 the cherty limestones of Derby shii-e, yield a D^ fauna, which 

 somewhat resembles that of the localized development of the 

 LonsdaJeia Subzone in the south-western part of the Midland 

 area, in the region of Waterhouses. 



A typical D, development is not present in Leicestershire, 

 although the upper barren dolomites of Ticknall may represent 

 part of the Cyathaxonia Subzone of other districts. 



The Pendleside Beds are poorly represented by about 30 feet of 

 blue shales, which are succeeded confoniiablv bv the Millstone 

 Grit. 



