388 Geological Society. 
A paper was then read, “ On the characters of the fossil trees lately 
discovered near Manchester, on the line of the Manchester and 
Bolton railway; and on the formation of Coal by gradual subsidence ;” 
by John Eddowes Bowman, Esq., F.L.S. communicated by the 
President. 
The paper commenees with a few preliminary remarks on the 
theory of repeated subsidences of the land during the carboniferous 
zra; and on the drift theory, the author being of opinion that the 
former receives much support from the phenomena presented by 
the fossil trees found near Manchester, and that it affords in return 
great assistance in explaining the peculiarities of their position. 
Mr. Bowman does not deny that plants may have been carried into 
the water from neighbouring lands, as in the instances of fern-fronds 
and other remains scattered through the sandstones and shales ; but 
he conceives it is difficult to understand whence the vast masses of 
vegetables necessary to form thick seams of coal could have been 
derived, if drifted; and how they could have been sunk to. the bot- 
tom, without being intermixed with the earthy sediment which was 
slowly deposited upon them. He is of opinion also, that without a 
superincumbent layer of mud or sand, to retain the hydrogen during 
the process of bituminization, ordinary caking coal could not have 
been formed. Another difficulty, connected with the drift theory, 
Mr. Bowman says, is the uniformity of the distribution of the vege- 
table matter, throughout such great areas as those occupied by the 
seams of coal, extending in the instance of the lower main seam of 
the great northern coal field, over at least 200 square miles; and in 
that of a thin seam below the gannister, or rabbit coal, in a hnear 
direction of thirty-five miles from Whaley Bridge to Blackburn. 
On the contrary, he believes, that it is much more rational te sup- 
pose, that the coal has been formed from plants, which grew on the 
areas now occupied by the seams,—that each successive race of 
vegetation was gradually submerged beneath the level of the water, 
and covered up by sediment, which accumulated till it formed an- 
other dry surface for the growth of another series of trees and plants,— 
and that these submergences and aceumulations took place as many 
times as there are seams of coal. He also explains the thinning 
out of the seams and other strata of the coal measures, by irregu- 
larities in the mode or extent of the depressions. 
Mr. Bowman then proceeds to the examination of the phenomena 
presented by the fossil trees discovered on the line of the Manchester 
and Bolton railway, and described by Mr. Hawkshaw in the pre- 
ceding communication: it will be necessary tu notice therefore 
only those points which did not- claim that gentleman’s more 
particular attention. Mr. Hawkshaw describes generally the mark- 
ings on the internal casts of the trees; but as it is difficult to convey 
a correct notion of their waved and anastomosing characters either 
verbally or by reduced drawings, Mr. Bowman applied paper to the 
surface of the stems and carefully traced the grooves or furrows by 
following them exactly with an instrument. The only indications 
of scars, which he could find after a long and close search, were at 
