RECORD: Darwin, C. R. Geological diary: [geological specimens numbered 1625-1692, descriptions]. [nd] CUL-DAR34.36-39 Transcribed by Kees Rookmaaker, edited by John van Wyhe (Darwin Online,

REVISION HISTORY: Transcribed from the microfilm by Kees Rookmaaker 2.2011. 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.

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.


A 1662 (not p 2), earthy very soft, fine, dirty white sandstone

B 663 — soft conch fracture, clay-stone: decomposing

B (do) 663 664 small angular fragments, whitish, salt taste —

C. 664 665 (not for), hard conch fracture, fine grained, white Feld[spar]

D 664 666 whitish, yellowish, hardish, earthy feldspathic rock

E 667 same as (673)

F 668 not effervesce, white hard, rough fracture, feld rock with [obscured]

G 669 white hard conch fract, fine grained, [illeg] feld rock (minute grains of quartz?)

H 670 dike white feldspathic rock fract black mica, green crystals quartz

J 671 mixture of crystal of quartz, mica, feldspar cemented by ferruginous matter

M 672 yellowish feld rock, hard earthy conch: fracture (not for)

N 673 whitish yellowish hard semi-crystall. porphyry with imbedded white crystals

O 674 hard earthy red porphyry abounding with white earthy crystals

P 675 [illeg] the chalk for very earthy soft feld rock specks of quartz

P 676 681 Feldspathic rock, hard very fine conch of mica with some crystals

Q 677 Fine, dull red Porphyry hard conchoidal fracture square white crystals, very little quartz

36 verso

B 2 3 688 white, softer much [illeg] quartz particles

B 4 689 Reddish do do do

C 690 more perfectly porphyry than (684) of which rock this is a continuation

D 691 Porphyry white earthy feldspar in small patches or layers like that of 2 Hills in & close same bed in sand

692 White Porphyry or Feldspathic rock, hard versicular with quartz in common

red Porphyry



37 verso [blank]


1655 — pale reddish brown, porphyry slightly vesicular with few small crystals of the 3 minerals

656 reddish purple with pale specks or imperfect crystals of earthy feldspar

657 Bluish reddish porphyry mingled together in concretionary vesicular with few crystals of glossy feldspar, quartz &c

658 [illeg] where fragments of extraneous porphyry appear to be imbedded in a basis of reddish

659 do do

38 verso

additional notes

1634: 1635: pale purple porphyry; small cavities — white patches forming oblong masses so as to give certain degree of a laminated appearance

1636 a compact variety of Porphy. with squ white angular white patches or crystals of earthy feldspar; very slightly laminated; together with other variety with quartz

1643. 1644. base porphyry with much iron? vesicular cavities lined with quartzose rock & containing crystals of quartz. —

1647 is evidently more clearly porphyritic than (648) they occur close together

1649 Bare feldspathic patches of quartz & small pebbles of porphyry

1652 Basis red porphyry crystals of quartz, white earthy feldspar & mica

1654 Compact pale purple, tough porphyry with few crystals of earthy variety [illeg] River cavernous, irregularly papform. —


642. 643. — Pitchstone — occurring in a bed beneath Porphyry — Opposite GuanacĂ o island cavernous, small quartz crystals & [illeg]

643, 644. Bed of rock in porphyry: do

646 — Containing much iron — in Porphyry

Guanacos Island

Cliffs West of anchorage

647. 648. — Varieties [illeg] of Jaspery rock (containing crystals above sandstone conglomerate. porphyry became [illeg]

649 — Sandstone conglomerate

650 — Compact semi semi-crystalline whitish feldspathic rock also above. — such rock as (640).

651. Chalky (with speck of flint) above Turritella?

(650) ∴

652 — Dyke cutting through the cliffs, friable, white uncrystallized feldspar, quartz [illeg] cavities lined with ox. of Iron

654 Commonest variety of Porphyry behind the fort.

39 verso

1625 — Fragment of shells, Pectens &c. Banana soft [illeg]

1626. 27. 28. 29. — Area — Turritellae. rock abundant

1630 — Turritellae

1631 do

1632 Hinge of very large shells

1633 Salt from a deep flat muddy valley in small plains: —

1634: 1635: Variety of Porphyry in laminae western foot of 2 hills

1636: The partly proof that the porphyry compact porphyry passes into the laminae

1637. 1638 — 2 compact varieties of porphyry with little feldspar & quartz lying above (1635) — All West hillocks of 2 Hills

1639 porphyry abounding with crystals of feldspar & quartz. very porphyritic variety. Brittanic rock

1640. white clay, sandstone — upper bed of great plain Calcarea at foot of 2 hills — soft —

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Citation: John van Wyhe, editor. 2002-. The Complete Work of Charles Darwin Online. (

File last updated 2 July, 2012