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THE HALIFAX COAL STRATA. 
BY JAMES SPEXCER. 
(Bead October 7th, 1897.) 
The Yorkshire coal field is divided into three horizons, viz.^ 
Lower, Middle, and Upper. 
The Lower Coal-Measures appear to have first been worked at 
Halifax, and thence the mines were gradually extended around the 
out-crop of the coal-field, and the two workable beds of coal wrought 
in them became know^n as the "Halifax Hard and Soft Bed coals." 
The Halifax coal strata form a compact group of rocks, consist- 
ing of beds of shale, sandstone, rag, bind, coal, seat-earth, gannister, 
ironstone and fossiliferous beds of marine and freshwater origin, the 
whole being enclosed between the Rough Rock at the base and 
crowned by the Northowram and EUand Flagrock. These strata 
are also well known to geologists on account of the great number 
and variety of their fossil contents. The marine beds overlying the 
Hard Bed coal have yielded a large number of marine fossil shells 
and fish-remains to our local collectors, and more recently the rich 
and various assortment of Fossil Plants shewing their internal 
structure found in our coal-balls, have extended the fame of our 
Halifax Coal strata over the civilized world. 
The conditions attending the formation of the different beds 
were of a very varied character, and the area in which they w^ere 
deposited was sometimes a land surface, covered by extensive forests 
of lepidodendrons, sigillarias, calamites, cycads and ferns in great 
variety ; at others a great estuary inhabited by molluscs and fishes, 
and into which the rivers of the period brought down spoils from 
the ancient land, such as sand and mud, trunks and branches of 
trees, etc., and into which the sea occasionally erupted and brought 
into the area marine shells and fishes. 
The fact that the Coal-Measures were deposited in a gradually- 
sinking area is generally admitted by geologists, and it has been 
suggested that the subsidence was probably caused by the immense 
