355 
COAL AND COLLIERY EXPLOSIONS. 
By C. E. DE RANCE, 
ASSOC. INST. C.E., F.G.S., HON. MEMBER MANCHESTER GEOL. SOC., 
OF H.M. GEOLOGICAL SURVEY OF ENGLAND AND WALES. 
F RINGTNGr the coasts of a large portion of Britain are lines of 
raised beaches, submerged forest beds, and inland tracts of 
peat, resting on marine and estuarine deposits, indicating a suc- 
cession of elevations and subsidences, characterized by periods of 
vegetable growth, alternating with still longer epochs of deposi- 
tion. Nowhere, perhaps, can this sequence be studied to better 
advantage than in the lowlands lying between the Mersey and 
the Ribble, and nowhere could be found better examples of the 
probable method of formation of the various measures and coal 
seams of the adjacent West Lancashire coal field. Careful 
examination of all the thicker coal seams show them to consist 
of distinctly stratified vegetable matter separated into groups 
by earthy partings, winch vary in thickness, even in different 
parts of the same colliery, and which, when followed to a con- 
siderable distance, are often found to not only expand, but to 
be associated with other sedimentary material, so that the two 
layers that form one coal seam at the first point, become sepa- 
rated into two distinct seams in the more distant area. 
An exact parallel to this may be found in most of the Lanca- 
shire mosses, thin planes of grey clay traversing the centre of 
the moss, gradually expanding towards tracts where the water 
was deeper and currents brought in foreign material, until the 
basin-shaped hollow was filled up, and the growth of peat went 
on. 
All who have studied geological sections, especially in their 
relation to the structure lines of scenery, will have noticed the 
tendency valleys have to occur along lines of anticlinal axes ; 
while the synclinals, or inward dips, constitute planes of strength 
which are noticeable in nearly all our hills of all geological 
ages, and especially in those which have longest withstood the 
wearing and degrading action of later denudation. The coal 
fields are, however, a noteworthy exception to this, for though 
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