r, to rocks which he deemed of igneous origin, led Hutton to
conclude that granite also must have been formed from matter in fusion;
and this inference he felt could not be fully confirmed, unless he
discovered at the contact of granite and other strata a repetition of
the phenomena exhibited so constantly by the trap-rocks. Resolved to try
his theory by this test, he went to the Grampians, and surveyed the line
of junction of the granite and superincumbent stratified masses, until
he found in Glen Tilt, in 1785, the most clear and unequivocal proofs in
support of his views. Veins of red granite are there seen branching out
from the principal mass, and traversing the black micaceous schist and
primary limestone. The intersected stratified rocks are so distinct in
color and appearance as to render the example in that locality most
striking, and the alteration of the limestone in contact was very
analogous to that produced by trap veins on calcareous strata. This
verification of his system filled him with delight, and called forth
such marks of joy and exultation, that the guides who accompanied him,
says his biographer, were convinced that he must have discovered a vein
of silver or gold.[105] He was aware that the same theory would not
explain the origin of the primary schists, but these he called primary,
rejecting the term primitive, and was disposed to consider them as
sedimentary rocks altered by heat, and that they originated in some
other form from the waste of previously existing rocks.

By this important discovery of granite veins, to which he had been led
by fair induction from an independent class of facts, Hutton prepared
the way for the greatest innovation of the systems of his predecessors.
Vallisneri had pointed out the general fact that there were certain
fundamental rocks which contained no organic remains, and which he
supposed to have been formed before the creation of living beings. Moro,
Generelli, and other Italian writers, embraced the same doctrine; and
Lehman regarded the mountains called by him primitive, as parts of the
original nucleus of the globe. The same tenet was an article of faith in
the school of Freyberg; and if any one ventured to doubt the possibility
of our being enabled to carry back our researches to the creation of the
present order of things, the granitic rocks were triumphantly appealed
to. On them seemed written, in legible characters, the memorable
inscription--

"Dinanzi