one of the few geologists who had taken a correct and enlarged view on the
subject.


LETTER 537. TO D. SHARPE.
Down [November 1846].

I have been much interested with your letter, and am delighted that you
have thought my few remarks worth attention. My observations on foliation
are more deserving confidence than those on cleavage; for during my first
year in clay-slate countries, I was quite unaware of there being any
marked difference between cleavage and stratification; I well remember my
astonishment at coming to the conclusion that they were totally different
actions, and my delight at subsequently reading Sedgwick's views (537/1.
"Remarks on the Structure of Large Mineral Masses, and especially on the
Chemical Changes produced in the Aggregation of Stratified Rocks during
different periods after their Deposition." "Trans. Geol. Soc." Volume
III., page 461, 1835. In the section of this paper dealing with cleavage
(page 469) Prof. Sedgwick lays stress on the fact that "the cleavage is in
no instance parallel to the true beds."); hence at that time I was only
just getting out of a mist with respect to cleavage-laminae dipping inwards
on mountain flanks. I have certainly often observed it--so often that I
thought myself justified in propounding it as usual. I might perhaps have
been in some degree prejudiced by Von Buch's remarks, for which in those
days I had a somewhat greater deference than I now have. The Mount at M.
Video (page 146 of my book (537/2. "Geol. Obs. S. America." page 146. The
mount is described as consisting of hornblendic slate; "the laminae of the
slate on the north and south side near the summit dip inwards.")) is
certainly an instance of the cleavage-laminae of a hornblendic schist
dipping inwards on both sides, for I examined this hill carefully with