RECORD: Darwin, C. R. Geological diary: At C. Espirito Santo, high cliffs commence. CUL-DAR34.194-195 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 4.2011. 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.
At C. Espirito Santo, high cliffs commence which abound with horizontal lines. & are white & brown & fine grained with much worn darker superior bed. — these end about Lat 52°. 48, where there are curved darker lines as at Cape Virgins — 4 miles more to the South no lines. — former cliffs lofty. —
Feb 17th.  St Sebastian bay. SE. side. cliffs. 200 - 300 feet. — composed of earthy sandstone,
tolerably hard, more or less pure. contains very few small pebbles of quartz slate & granitic rock in some places small beds of pebbles. — in lines Pholas, Turritellae — Venus not common) remains of Cancer & very numerous impressions.
Beech leaves & pieces of wood (1847 .. 1851). — leaves former seams In some parts there was much detritus & gravel & in upper parts, but generally this soft earthy sandstone (there are layers of hard sandstone (1848) or rather — semi-bed-semi concretion). — (concretions always are an attempt to form a bed)
The beds are generally inclined & slightly curvilinear, never remain for 20 yards the same; common dip
to South ∠ 20°. — the upper beds which are more ferruginous, have repeatedly cut away & replaced the lower
in with basin strata: — The inclination of these strata is entirely owing to currents. — (∴ lower are horizontal where upper contorted). On the ground above were blue Mytili. — (some of the ground in the neighbourhead must be near 400 feet high). — I should conjecture, that this bay & useless had once been joined?). —
These beds are clearly of same age with Magellan St alluvium, but the finer substances only deposited & more stratified. — I should think it must have been a bay, where a stream entered; muddy from the Pholades: (∴ quiet, not subject to regular current) yet such occasionally happened (during floods?). — It is interesting to see the leaves of the Fagus & still more to find so hard a
sandstone in alluvium (1848).
The Beagle Channel & Sts of Magellan (& probably Useless Bay) [afformed] main exit for this alluvium intermediate [span] protected by C. Monmouth & Hose Peak, produced this deposit;
When the Sts of Magellan were cut through this filled of detritus, the low land which connects St. Sebastian & Useless bay (in line) was cut through & (even if the water has not
b even lately been joined). —
On the SE coast were some immense blocks of crystalline rocks, perhaps deposited at this period. — One of syenite hard. mean height above the sand of 5 feet. (shape oblong, with roof like a barn), in circumference 47 feet. (How much below sand!?). — Several others were half & 2/3 of this great size. — They clearly do not come from the alluvial cliffs & here this bay is not exposed.
These cliffs give argument that Magellan beds were deposited under ordinary circumstances. —
more inclined ∠ 20°
There were heads, dung, immense numbers & holes of Toco Toco. excellent connecting animal
from dead leaves. some slate of vegetation during present elevation
This geology interesting as extensive & very modern section of ocean bottom:
18th [February 1834] Between C. Sebastian & Penas; country very undulating; the higher land
tab being nearly 1000 feet high & part wooded. I should think all alluvium: — Where there are cliffs it is rather browner & without many lines. —
19th. [February 1834] Cape Ines. Wood brown. St. Ju[lian] porphyry pebbles brought up by lead! — Cliffs. much the same, rather darker & harder. — lines not quite horizontal. — The Porphyry pebble at bottom are universal in Lat. 54° 22', but they are coarser & more siliceous than Port St Julian. Yet general same color. — Lat 54.22' looking same there were hills 5 or 6 miles evidently slate. — there were alluvial cliffs which extend for some miles further & then die away. — There were small ones near <two words missing?>. —
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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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