206 
GEOLOGY: E. C. JEFFREY 
PETRIFIED COALS AND THEIR BEARING ON THE PROBLEM 
OF THE ORIGIN OF COALS 
By Edward C. Jeffrey 
BOTANICAL LABORATORY. HARVARD UNIVERSITY 
Communicated by J. M. Clarke. February 3. 1917 
In recent years I have published two preliminary articles on the 
conditions of formation of coal based upon a study of the internal 
organization of a large niunber of coals from various geographical regions 
and different geological horizons.^'^ The success of these investigations 
has been based on improved methods, which are recorded in an article 
recently published.^ The conclusion reached, contrary to the usually 
accepted opinion supposed to be based on reliable stratigraphic evidence 
is that coal is not in general a deposit laid down in situ but is composed 
of drift materials deposited in open water. The arguments from struc- 
ture for this opinion seem to be overwhelming, for the typical organiza- 
tion of the nimierous coals investigated is entirely canneloid. Since 
cannel coal is universally conceded to be a deposit accumulated in open 
water, it follows that the great mass of coals must have been accumu- 
lated under similar conditions to those admitted for cannels and oil 
shales as a consequence of their structure. The present writer accord- 
ingly on the basis of new facts arrived at by new and improved 
methods, must announce his adhesion to the doctrine of coal formation 
long held in France, namely that this invaluable mineral is formed of 
drift material laid down in open water and does not correspond at all 
to the peat deposits formed on land in the present epoch and in temper- 
ate climates. 
The strongest argument supplied from the structural standpoint for 
the origin in place of coal is that provided by petrified coals, or as they 
are often designated 'coal balls.' A very interesting summary account 
of these structures, with special reference to those occurring in the 
British Isles, was published some years ago.* The conclusion is here 
reached that the Upper Foot Seam as well as other English and Conti- 
nental seams af higher and lower geological level, which contain the masses 
of petrified vegetation known as 'coal balls' consist of vegetable materials 
accumulated in sea water or at least water that was saline. The pres- 
ervation of the remains during the years of accumulation is attributed 
to the antiseptic properties of sea water. It is apparently an unneces- 
sary assumption since very delicate vegetable structures are found at the 
present day at depths of from three to ten meters in post glacial lacus- 
trine accumulations. It must further be pointed out that the laying 
