erlying tuff? Or, again, I see no difficulty in a mass of
trachyte being exposed by subsequent dislocations and bared or cleaned
by rain. At Ascension (page 40), subsequent to the last great aeriform
explosion, which has covered the country with fragments, there have been
dislocations and a large circular subsidence...Do not quote Banks' case
(485/3. This refers to Banks' Cove: see "Volcanic Islands," page 107.)
(for there has been some denudation there), but the "elliptic one"
(page 105), which is 1,500 yards (three-quarters of a nautical mile)
in internal diameter...and is the very one the inclination of whose
mud stream on tuff strata I measured (before I had ever heard the name
Dufrenoy) and found varying from 25 to 30 deg. Albemarle Island, instead
of being a crater of elevation, as Von Buch foolishly guessed, is formed
of four great subaerial basaltic volcanoes (page 103), of one of which
you might like to know the external diameter of the summit or crater
was above three nautical miles. There are no "craters of denudation"
at Galapagos. (485/4. See Lyell "On Craters of Denudation, with
Observations on the Structure and Growth of Volcanic Cones," "Quart.
Journ. Geol. Soc." Volume VI., 1850, page 207.)

I hope you will allude to Mauritius. I think this is the instance on the
largest scale of any known, though imperfectly known.

If I were you I would give up consistency (or, at most, only allude in
note to your old edition) and bring out the Craters of Denudation as
a new view, which it essentially is. You cannot, I think, give it
prominence as a novelty and yet keep to consistency and passages in old
editions. I should grudge this new view being smothered in your address,
and should like to see a separate paper. The one great channel to
Santorin and Palma, etc., etc., is just like the one main channel
being kept open in atolls and encircling barrier reefs, and on the same
principle of water being driven in through several shallow breaches.

I of course utterly reprobate my wild notion of circular elevation;
it is a satisfaction to me to think that I perceived there was a screw
loose in the old view, and, so far, I think I was of some service to
you.

Depend on it, you have for ever smashed, crushed, and abolished craters
of elevation. There must be craters of engulfment, and of explosion
(mere modifications of craters of eruption), but craters of denudation
are the ones which have given rise to all the discussi