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 Darwin Online images 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.

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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