RECORD: Darwin, C. R. n.d. Geological diary: Re-examination of the transition fully confirms very thing I then said. CUL-DAR34.74-75. Edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed by Kees Rookmaaker, corrections and editing by John van Wyhe 3.2011. RN1

NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. This document, part of the largest scientific document composed by Darwin during the voyage of the Beagle, is written mostly in ink. Marginal notes are here integrated into the text.

Reproduced with the permission of the Syndics of Cambridge University Library and William Huxley Darwin.

See the introduction to the Geological Diary by Gordon Chancellor.


74

Re-examination of the transition fully confirms every thing I then said. — 1st 18 like 1895

2d then rock, alluded to me as dubious, such as (1893). — in every degree of purity:

3d (1895), where inspection at once shows identity with the quartz range. —

4th again here (1893). becoming leaner & finer till in about 1/4 of a mile we have (1896). where slaty structure & cleavage first became apparent. & lastly (1897). when blue slate is apparent. — We afterward have [illeg] green clay slates. —

I hammered every inch of this mile of coast. — where there was no sign of superposition. but endless one of lateral clea transition. — Again proceeding. we come to such as (1893) (& more of & 1895) which in the span of 20 yards pass into pale slate. which then extends for some distance

74v [blank]

75

The full admission admits many difficulties: here the quartz ranges separated cleavage power & contorted by do. — Was the slate & hills of same elevation till altered by degradation. —

If we admit that the quartz lies beneath these rocks. & was elevated. we must suppose the arches formed in unbroken rock. — if at period it was soft; for how many ages after deposition must it have remained so, during formation of beds of shells & masses of rocks. —

Or shall we suppose during quartz formation the upheavals continued took place & that subsequently. the transition rocks (& even pure quartz) continued to be formed. chiefly in the valleys. or if even the crests. the violence aging. earthquakes would have removed them: On this supposition, we only have the [illeg] of coincident mass of [illeg] & elevations

75 verso

the good section at base of quartz hills would prove all this : but wherever a section might be expected of superposition a transition is only found. —

The tips of the slate might been averted, but could for its nature seldom show:

What is it more tha

The quartz cleavage is like on a gigantic scale; tortuous cleavage: in mica slate

at. M. Video [sketch]


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Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

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