418 
TITE LAST DECADE. 
Professor Arnold Lupton, of the Yorkshire College, contributed 
notes on the Midland Coal-field. In the proceedings for 1880, the 
Rev. J. Magens Mello gave an account of investigations which 
he with others had made in Cresswell Caves in Derbyshire, and Mr. 
W. H. Wood gave the result of experiments which enabled him to 
distinguish obsidian from black blast furnace slag, the former con- 
taining nearly double the percentage of silicia as compared with the 
slag. Professor L. C. Miall read a paper on the structure of the skull 
and some other bones of Ctenodus. Mr. Davis read a paper on the 
distribution of fossil fishes in the Yorkshire Coalfields, and enumerated 
all the genera which had been found associated with the several beds 
of coal. The total number of species of fossil fishes hitherto dis- 
covered was fifty-one. The same author also described a gi'oup of 
erratic boulders at Norber, near Clapham. Norber is the southern 
extremity of a long promontory of mountain limestone extending 
from the base of that portion of Ingleboro' called Simon's Fell. On 
its western flank are escarpments overlooking Clapdale, and on the 
opposite one precipitous ridges extend for nearly two miles in a 
northerly direction, towards the head of the dale overlooking the 
Crunimack Valley. The escarpments of the limestone extend across 
the upper part of the dale, and on the eastern side constitute Mough- 
ton Fell. The whole of the surface of this limestone plateau is 
thickly strewn with masses of Silurian grit, some of immense size 
and weighing many tons. Blocks, sixteen to twenty feet in diameter, 
are not uncommon, and many of them are raised on a pedestal of 
limestone, in some instances nearly two feet in height, the surrounding 
limestone having been denuded to this extent since the Silurian blocks 
gained the present locality. Towards the head of the valley the 
limestone becomes much thinner, and Silurian rocks are exposed, and 
it is from this source that the perched blocks have been derived. 
They have been carried by a great glacier which descended on the 
western flank of Ingleboro' towards the vale of the Ribble. Numerous 
scratches on the rocks show the direction of this glacier, and its power 
and thickness are indicated by the force with which it tore up the 
Silurian grits and carried them over the limestone deposit, in some 
instances two or three hundred feet higher than their original position. 
