SPENCER : GNEISSOID GRANITE IN THE HALIFAX HARD BED COAL. 99 
there are three separate layers, chiefly composed of Anthracosia, 
indicating marine or estuarine deposits, while the Hard Bed Coal has 
been fully demonstrated by microscopic examination of the admirably 
preserved plants which occur in it, to be a land deposit. Immediately 
overlying the coal a bed of marine shells, Aviculopecten papyraceous, 
occurs, followed by some yards of strata containing Goniatites Listeri, 
and other marine shells. Here then we have evidence of great changes 
of level indicated in these strata, during which the currents bringing 
deposits may have varied considerably. But there may have been 
other changes of level having important bearings upon the formation 
of coal and other matters in connection with the deposition of strata, 
which have either left no traces behind or they are so obscure as to 
have hitherto escaped observation. 
The boulder of Gneissoid Granite for instance, now under notice, 
was found in the midst of coal which was not disturbed, or in 
any way differently disposed from the rest of the coal bed. This 
may indicate a slight depression of the area so as to bring it 
within the influence of the tides, or the area may have been near a 
large estuary which was subject to occasional floods, during which 
the boulder may have been brought down on floating masses of vege- 
table matter, or entangled in the roots of a tree and deposited in the 
submerged area. That the area now occupied by the Hard Bed Coal 
was occasionally subject to incursions of the sea, or at least over- 
whelmed by water containing Carbonate of Lime in solution, is proved 
by the abundance of calcareous balls, containing coal-plants, found in 
the midst of the coal . It has been suggested that these far-travelled 
boulders, found in coal, may have been brought by icebergs, but this 
idea does not seem to be supported by the facts. So far as I could 
gather, and I happened to be on the pit-bank when the one under 
notice was brought out of the pit, this boulder was not accompanied 
by any other detritus such as sand or clay or smaller pebbles, which 
might reasonably have been expected had ice been the carrying 
agent ; and such is the case I am informed wherever the boulders are 
met with in coal beds. It seems to me, therefore, more reasonable 
to attribute their transportation to drifting and tangled masses of 
vegetable matter rather than to ice. 
