118 
THE GEOLOGIST. 
that conveyed tlie drift, but are specimens derived from decom- 
posed boulders of mountain limestone. The sands and gravels 
of Preswicb and Middleton afford very beautiful specimens of the 
Syringipora ramulosa, Cyatbopbyllum basaltiforme, and several 
other species. The fossils are quite free from any matrix, and 
look as if they had been detached from the spots on which they 
lived ; and never had been imbedded in Hmestone. They owe 
their present state, no doubt, to water containing carbonic acid 
gas, having percolated through the strata, and removed all the 
carbonate of lime composing the matrix of the fossil ; while the 
fossil itself, though composed of carbonate of lime, from some 
cause hitherto unexplained, has remained untouched. The same 
effects are seen in the fissures of the mountain limestone of Der- 
byshire, through which waters charged with carbonic acid flow. 
No. 4 deposit consists of beds of brown clay generally, but not 
always free from pebbles. It might be classed with the last- 
described deposits, as it no doubt inosculates with them ; but I 
have put it by itself for the purpose of distinguishing it from the 
regular till (No. 2). The greatest thickness which I have heard 
of is at Jericho Clough, between Failsworth and Droylsden, 
where Mr. Bradbury found it seven yards thick. It is seen in 
Higher Broughton, on the Oldham Railway, near Fox Denton, 
and at other places. At Captain Fold, near Heywood, Mr. 
Thomas Livesey informs me that it exceeded twelve yards in 
thickness. As yet no fossil organic remains have been found in 
it. No. 5 deposit consists of beds of fine and coarse gravel and 
sand found in the valleys and low lands now traversed by rivers 
and streams, and has evidently been derived from the beds 1, 2, 
3^ and 4, before described. It is sometimes stratified, and fre- 
quently unstratified, and cannot easily be distinguished from 
No. 3, except from the position in which it is now found.^'' 
Mr. Binney closed his communication with a list of the sec- 
tions he had obtained, and an appeal to the members generally 
to fm-nish facts on this subject, so that all the various appear- 
