RECORD: Darwin, C. R. Geological diary: Re-examination of the transition fully confirms very thing I then said. CUL-DAR34.74-75 Transcribed by Kees Rookmaaker, 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: 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.
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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.
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
74 verso [blank]
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
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, editor. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)
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