Editorial Comment. 199 
phism. The immediate contact zone of the schists is not diff- 
erent from the schists at some meters distant from the i^ranite. 
2. It is hardly in accordance with known contact metamor- 
phism, nor with any observed nor hypothetical case, that an in- 
trusive rock should impart to the intruded rock siliceous ele- 
ments that should arrange themselves in banded order, such as 
seen in the gneisses and gneissic schists extending for such 
distances in successive alternation. 
3. It is impossible to believe that a granitic intrusion 
should cause the formation by infiltration of siliceous elements, 
of a banded gneiss or of granite within the schists at a distance 
say of a quarter of a mile from the known intrusive rock. 
4. There is an easier and more natural explanation of the 
origin of the gneisses and schists, by supposing them to have 
existed as sedimentary strata of varying acidity, subjected to 
profound regional metamorphism, in the application of which 
were concerned both dynamomietamorphism carried to actual 
plasticity of the fragmental materials, "magmatic" intrusion of 
some of the fused materials amongst the parts not plastic, and 
pneumatolitic transference of much acid matter amongst the 
same,forming pegmatytes and veins. This slow process was 
the cause of the total recrystallization of the fragmental materi- 
als in situ, so far as the same were not extruded as lavas, thus 
accounting for the absence of vitreous matter. This method of 
origin does not require the extraction of so much silica from the 
magmatic granite and its dissemination amongst the schists as 
to leave it a basic rock, nor the loss of so much basic material 
by the schists as to render them acid : it only requires that the 
elements pre-existing in the fragmental strata shall be heated, 
pressed and re-crystallized in situ in the presence of moisture 
or rendered plastic. The granite and the schists and gneiss 
then would date from the same epoch, and be derived from the 
same elements, differing in kind because of the variability of the 
dynamic force in its geographic application, and because of the 
variability of the original stratified mass. 
5. All the ascertained facts, whether structural, chemical, 
petrographic or petrologic, would find consistent causes, with- 
out resort to hypothetical or doubtful processes. 
The phenomena that have been studied by the authors are 
parts of a larger problem than that they have applied themselves 
