pressly
said so, to obliterate the " metamorphic and metasoma-tic schools." By
it he assumed a mineral " protoplasmic mass " which, as the result of
crystallization and cooling, " had already become porous." Then
followed an outflow of hot waters which dissolved and removed from the
protoplasmic material silica, alumina, and potash, adding lime,
magnesia, and soda, which " must have necessarily altered by degrees
the composition of the porous mass, heated from below, penetrated by
aqueous solutions, and rendered more or less plastic in parts. In the
changing mass, moreover, took place processes of crystallization,
followed by partial separations determined by differences in specific
gravity between the species thus formed. In this way were produced
various types of plutonic rocks which may be justly called " Primary."
T. Sterry Hunt would refer the crystalline Manhattan schists to these
Primary rocks. As to the gentle folds {plica) so
characteristic of these rocks, he said " decrease of volume beneath
the crenitic covering (the area of the schists) must have resulted in
movements giving rise to the more or less marked corrugations
everywhere met with in the earlier layers of the crenitic envelope."
Probably this view to-day would receive little more than an antiquarian
attention.
