In the coal-field of Midlothian the seams of coal vary from 2 feet to 5
feet in thickness. One of them is known as the "great seam," and in spite
of its name attains a thickness only of from 8 to 10 feet thick. There
are altogether about thirty seams of coal. When, however, we pass to the
continent, we find many instances, such as that of the coal-field of
Central France, in which the seams attain vast thicknesses, many of them
actually reaching 40 and 60 feet, and sometimes even 80 feet. One of the
seams in the district of St. Etienne varies from 30 to 70 feet thick,
whilst the fifteen to eighteen workable seams give a thickness of 112
feet, although the total area of the field is not great. Again, in the
remarkable basin of the Saone-et-Loire, although there are but ten beds
of coal, two of them run from 30 to 60 feet each, whilst at Creusot the
main seam actually runs locally to a thickness varying between 40 and 130
feet.
The Belgian coal-field stretches in the form of a narrow strip from 7 to
9 miles wide by about 100 miles long, and is divided into three principal
basins. In that stretching from Liege to Verviers there are eighty-three
seams of coal, none of which are less than 3 feet thick. In the basin of
the Sambre, stretching from Namur to Charleroi, there are seventy-three
seams which are workable, whilst in that between Mons and Thulin there
are no less than one hundred and fifty-seven seams.
Pages:
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144