The Meeting of the British Association at York. 179 
sometimes be traced in adjacent balls separated by a streak of coal. 
Again the balls are often very irregular, with sharp edges and fine 
fragments projecting, so that rolling after even partial fossilisation, 
as demanded by the “transport theory” seems impossible. The 
very local occurrence of the pockets of balls is not in accordance 
with the assumption that they lie in the track of streams. Only 
one perfect ball has been found in the floor of a seam; this 
contained Stigmaria only, which is in accord with the “ growth in 
place ” theory. Analysis also shews that this ball contains more 
clay than usual, which is what would be expected if it were formed 
in the floor of the seam. As to the association of the coal-balls 
with marine conditions, in every case in which the balls occur, 
marine shells (typically goniatites) were found in the roof of the 
seam. Where the “ Gannister” and “ Upper Foot” join to form one 
seam the nodules are found right through the seam, whereas when 
the two are separate they are only found in the upper one (with the 
“marine” roof). Experiments with living plants, which were 
submerged in sea-water with peat and decaying shell-fish, show that 
the plant-tissue remains perfectly fresh after nine months, while the 
animals had quite decomposed. The coal-balls are concretions of 
Ca C0 3 and Mg C0 3 , which probably result from the reduction of 
the sulphates of the sea-water by the decaying plant. 
Mr. Bolton of Bristol argued that as there are many marine 
horizons in the Coal-measures, the coal-balls should on the theory 
of Binney be more widely distributed than they actually are. He 
thought that they might owe their origin to the fragmentation of a 
basement bed of peat. The country was in a constant state of 
unrest during the Coal-measure period. 
Mr. James Lomax brought forward certain facts which seemed 
to him to support the river-transport theory of the origin of the 
nodules; for instance that quite different plants are often found in 
adjacent nodules. He also stated that certain seams bearing coal- 
balls have no goniatite roof-nodules. 
Mr. Watson attacked the views of Mr. Lomax, denying that 
goniatite nodules are absent from the roofs of coal-ball seams. 
Other speakers having contributed to the discussion, criticising 
the details of the chemical processes hypothecated by Miss Stopes, 
Mr. Teall, the Director of the Geological Survey, supported the in 
situ theory and remarked that an enormous amount of sea-water 
would be required in the process of formation. This might be 
supplied by diffusion. 
