Note 205 — Chapter XXI

I extremely regret not having been at this time acquainted with Mr. D. Sharpe’s able essays on the foliation, cleavage, etc., of slaty rocks, gneiss, etc., in the Geological Society’s Journal (ii. p. 74, and v. p. 111), and still more so with his subsequent papers in the Philosophical Transactions: as I cannot doubt that many of his observations, and in particular those which refer to the great arches in which the folia (commonly called strata) are disposed, would receive ample illustration from a study of the Himalaya. At vol. i. p. 309, I have distantly alluded to such an arrangement of the gneiss, etc., into arches, in Sikkim, to which my attention was naturally drawn by the writings of Professor Sedgwick (“Geolog. Soc. Trans.”) and Mr. Darwin (“Geological Observations in South America”) on these obscure subjects. I may add that wherever I met with the gneiss, mica, schists, and slates, in Sikkim, very near one another, I invariably found that their cleavage and foliation were conformable. This, for example, may be seen in the bed of the great Rungeet, below Dorjiling, where the slates overlie mica schists, and where the latter contain beds of conglomerate. In these volumes I have often used the more familiar term of stratification, for foliation. This arises from my own ideas of the subject not having been clear when the notes were taken.