118 SECTIONS TO CONNECT THE LANCASHIRE 
field was made under the superintendence of Professor A. H. Green, 
assisted by Messrs. R. Russell, J. R. Dakyns, J. C. Ward, C. Fox- 
Strangways, W. H Dalton, and T. S. Holmes. Several small memoirs 
were issued explanatory of quarter sheets from time to time as the 
work progressed, the whole culminating in the great memoir pub- 
lished in 1878, under the editorship, and in great part written by, 
Professor Green. In the dedicatory notice preceding the work, Mr. 
Bristow states tliat " it is a pleasant duty to acknowledge the valu- 
able assistance which the officers of the Geological Survey have 
received from colliery proprietors and others who have given informa- 
tion, without which the memoir could not have been made as complete 
as it now is." The members of the survey collected and recorded all 
the information that could be obtained from workings in the pits, 
information which will be of great value, when the beds of coal now 
worked are finished and others at a greater depth have to be sought 
for ; but at the same time information having heretofore a precarious 
existence, and Uable to be lost when the colliery to which tliey belong 
is exhausted. From what has already been stated it may easily be 
conceived that the work done by the members of this Society in the 
collection and comparison of sections obtained in sinking pits and 
trial borings ; in the correlation and identification of the several coal 
seams ; in the formation of horizontal sections ; and observations 
made during the progress of railway undertakings would be of no 
small value to the Geological Surveyors, and a reference to the 
memoir will show how readily these observations have been placed at 
their disposal. 
It must not be supposed, however, that this branch of the Society's 
work is completed. In the introduction to the Survey memoir will 
be found this paragraph, — " The Yorkshire Coal-field is comparatively 
speaking virgin gTOund, along its western and northern outcrops 
mining operations have been indeed vigorously carried on, but these 
are, so to speak, bassett workings, exceeding in very few instances a 
depth of 200 yards ; the great spread of exposed Coal Measures in 
the centre of the basin is untouched, and the portion beneath the 
Magnesian Limestone is pierced by only a few shafts." 
