RECORD: Darwin, C. R. Geological diary: [Concepcion March 1835] Fort Galvez. [3.1835] CUL-DAR35.354-356 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 8.2011. RN1

NOTE: Part of these notes were apparently taken in the field as an aide memoire for Darwin's investigation of the Concepion earthquake of 1835. They inform many passages of his account in the Beagle diary pp. 129 ff.

Editorial symbols used in the transcription:
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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.


354

March 5th. [1835] — Fort Galvez. — near the Beach, junction slate exactly the same as I have called ampelite, together with greenish talcaceous slate — more glossy, but like the brown one ([blank]) — cleavage most singularly convoluted. —

[sketch] ∠ 42° (horizontal section. 2 yards by 2: — [sketch] vertical section where a horizontal line of fault seems to have caused the curvature. — in other places perhaps they were original.

quite impossible to know the true dip. — This point which forms the Harbor, is covered up by the tertiary strata, so as to form a strip of plain: —

March 6th. [1835]— Linguen. — Well known as seat of best coal: —

Cliff about 100 ft high. — upper part, red earth, as in Quiriquina. — (which is marine deposit). beneath which are soft sandstones. — in which lie the coal beds of lignite:

The accompanying section is the result of the examination of different parts of fallen down cliff. —

[sketch] 10 9 7 x much bigger 6 5 4 3 2 1
30 100

(1) very soft sandstone containing numerous pebbles such as Quiriquina.:
2 Ferruginous fine grained sandstone. —
(3) Very irregular layer, many places about a foot wide of lignite. harder & not not so glossy as generally. (2574). mingled with in layer of pebbles. must have been deposited in stream curvilinear, extremities suddenly truncate, or thins out & dies away:
(4) a more compact sandstone, containing large [illeg] of fine grained very hardy calcareous sandstone: in other place the bed is partly made of a hard sandstone with grains of pure quartz (2575): in structure similar to those in Quiriquina

354 verso

B. Blanca Bird. Callandra — Thesosoma. Sturnus. Ruber

4th [March 1835] Reached Concepcion (3d earthquake of sea Mocha) Landed

Quiriquina — good geology — Wrecks on coast cotton below roofs chairs tables &c &c &c returned late at night Landed at Talcuana & scarce — Rode to Concepcion. [great cracks]; cheerful slate church

Buttresses [illeg] danger — Ladies in Ponchos — place of town like old cities —

Height of wave — soft pools — escape of child. boat SW & NE (compass); Walls stand better than shore.

Through vibration from Andes; Rode distance of parrapets — Heavy rain. — Rotten. —

deaths owing to time of day [illeg]. Home & man fell down. cattle wild with fright, fell over promontory

Say owing to Indian to open having stopped Anteri[illeg]

: From 4 years : Sea height of — Hot water some spring stopped some flow too much. — immense degradation, solid rock: shivered — wonder referred — villages — fires an appalling sight — bitterness of height — some manufacturers effect on England — Corcovado fine weather. When active: here when northerly wind flocks of gulls. —

repeated subsequent earthquakes. — Scenery of Concepcion

page in pencil, 'B. Blanca Bird.' in ink

355

but paler colored: — soft ferruginous sandstone:
(6) main layer of coal. (is now covered up so could not see it) said to be one yard thick: the lignite is very black. glossy but of little specific gravity: This has been the mine, & the very best & most abundant source of the working. (2570: 71: 72):

(7). exceedingly soft sandstone or rather coarse sand, just cemented together 2576, with ferruginous curvilinear bans (2577): This may represent the common sandstone of upper part of cliffs: there are curve twisted ferruginous water lines. — The upper part of this passes into an aluminous aluminous bed, with a rubbly fracture (just similar to what is found in Quiriquina) (2578): In all these sandstone there are innumerable lines of lignite from the thickness of paper to that of a shilling: (The formation in section is not thick enough)

(8) Soft rubbly lignite (2573) not worth any thing, about a foot thick, irregular showing not quite undisturbed deposition. —

(9) a whiter sandstone (like 2576) with more ferruginous lines & patches, contains unimportant layer of lignite.

(10) The upper of bright red. soft friable dry earthy substance. — It may be remarked that the soft sandstone (2576) is the principal substance which contains the lignite. — It is almost superfluous to say that this formation is identical with that of Quiriquina. — Where the mine is the strata are nearly horizontal but not very regular, perhaps probably owing to original

355 verso [blank]

356

(3)

a 200 yards to the North, the strata all dip to the NW at an angle 23° (even here not quite regular).

[sketch]

The lowest beds, described in the section, are here owing to upheaval here, but are not visible where the mine is. — I may also here remark that I saw inclined strata at a larger angle near Concepcion. — It is probably this inclination which has induced people to consider this formation as secondary: —

Where its real age is modern tertiary. — Perhaps it is part of same line of disturbance which has tilted strata at S extreme of Quiriquina???

NB. — The tilting of all these strata appear to have taken place when beneath the sea: even I am not certain whether some of red bed has not been deposited subsequently to this action. I judge from the plain superficies in some places, where the strata are inclined. —

Concepcion is like Valdivia. Tert: strata. predominant. —

At Concepcion numerous angular rocks of fine granite with large crystals of white feldspar: doubtless the formation is somewhere very near. — ؟ Road to Concepcion?

Cliffs close to Talcuan have also been worked for coal: the structure does not differ essentially from those described: the sandstone are more uniform in their nature: the calcareous sandstone concretions are numerous, but soft:

The coal is of a poorer quality; there are many layers of black of substance of earthy lignite or carbonaceous arth: is chiefly

356 verso

remarkable by quantities abundance of silicified wood & patches of lignite, as in Quiriquina. distinct from the regular layers. —

The stratification is nearly horizontal. —

Concepcion

March 1835


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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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