They are nodules contained in
the whin-stone, porphyry, or basaltes of the Calton-hill, by Edinburgh;
a body which is to be afterwards examined, when it will be found to have
flowed, and to have been in fusion, by the operation of subterraneous
heat.
This evidence, though most conclusive with regard to the application of
subterraneous heat, as the means employed in bringing into fusion all
the different substances with which strata may be found consolidated, is
not directly a proof that strata had been consolidated by the fusion of
their proper substance. It was necessary to see the general nature of
the evidence, for the universal application of subterraneous heat, in
the fusion of every kind of mineral body. Now, that this has been done,
we may give examples of strata consolidated without the introduction
of foreign matter, merely by the softening or fusion of their own
materials.
For this purpose, we may consider two different species of strata,
such as are perfectly simple in their nature, of the most distinct
substances, and whose origin is perfectly understood, consequently,
whose subsequent changes may be reasoned upon with certainty and
clearness.
Pages:
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102