RECORD: Darwin, C. R. 'Reflection on reading my Geological notes'. [3.1834] CUL-DAR42.148 Transcribed by Kees Rookmaaker (Darwin Online,

REVISION HISTORY: Transcribed by Kees Rookmaaker, corrections by John van Wyhe 10.2011. RN1

NOTE: This document is a continuation of CUL-DAR42.93-96. See the excellent fully annotated transcription and discussion by Sandra Herbert in Herbert 1995.

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Reproduced with the permission of the Syndics of Cambridge University Library and William Huxley Darwin.



It is impossible not to be struck with the vast scale on which geological facts take place in S. America —

Granitic rocks from the Orinoco to the Plata — (45° degrees of Latitude. —) with nearly the same cleavage not widely different.— Within this we have the 1000 1100 miles of Tosca. then of the great oyster formation, covered by the [blank] of Porphyry gravel:

With the exception of the Granite. this vastness (is in comparison to other countries) more apparent than real. — In Europe. We have the chalk from Ireland to Poland &c &c &c. — The real difference. consists, perhaps. in what I have alluded to. a greater rapidity in the elevation. In Europe. they were slow; formation after formation paved the bottom of the ocean: the each raised land was has been exposed to a greater length of alluvial action. & to the denuding effects of coasts. —

Moreover. many lines of elevation have crossed it — breaking & confusing the strata. — In this country all is regular & simple. — As Patagonia has risen from the waters in so late a period, it may be interesting to consider whence came its organized being. — I have conjectured the absence

148a verso

Is not the Entomology similar to Northern Traversia. V Ann. des. Science

Botany with Cordilleras & do.

Shells of rivers: S. Cruz. Negro. Sauce

Any Plants of/ productions of whole Patagonia remarkably similar

Porph. pebbles. Falkland. Sound.— & between off Staten Land: — Pebbles owe their origin N. of S. Cruz. judging from numerous boulders in S. Cruz & Tierra del Fuego.

at S. Cruz. I have a Cat.— Capt King procured other sort from the Indians

Strata without shells owing to Gypsum??? Yet at S Cruz. in close proximity. — ossiferous gypsum at Paris no shells: In Sicily Blue clay with do without shells Lyell. Vol. III. P. 64. — Crystals of selenite & some shells base of Etna. P 77.

Compare the certain & recent Elevations of Patagonia with Mr. Lyell map. of under water parts of Europe. — for extent & size. —

The gravel over R. Negro plain is one of the re-depositions after some elevations: therefore much posterior to Shingle bed & gr oyster: formation. — Tosca plain coeval with it. — Yet St. Fe limestone with similar shells. — shows perhaps. a quick succession of events & earlier death of same shells in Southern parts of hemisphere. —

I cannot quite see. how the Mastodon lived on Patagonian Plains?—(: is it Mastodon?. —



of trees in the fertile Pampas & rich valleys of B. Oriental. to be owing to no Creation having taken place subsequently to the formation of the superior Tosca bed: with respect to the Plants. I know nothing.— The Insects are few probably larger animals being of easier knowledge. best deserve observation. — We will consider only those animals South of the Plata.— (∴ less immediate communication with Brazil) It appears they nearly all are more characterized by a large Geographical range.—

& therefore may easily have travelled from their Northern original homes.— For instance the Mephitis or Skunk The Canis jubatus (found at the R. Negro) otter & common Fox (tricolor?). Jaguar. Puma. Gato pajero. found at B. Blanca & B. Oriental (there are other Cats. but I do not know them) even to Sts of Magellan).— Rats Mice my knowledge is not sufficiently accurate. about. — Nutria. — Toco Toco (& that sort with line on incisors). Cavia Cobaya. — (that is if the R. Negro & St of Magellan species are same with B. Ayres. & Paraguay.). Biscatche. Chili. & Brazil. Molina (Azara). the Dasypus. hybridus villosus. unicinctus). — Pecari. (found at R. Negro) Guanaco. — Cervus Campestris. — The only two good exceptions. which I could not find out, or see in books to occur further N. than 37°. 30′.is the Cavia Patagonica — & Dasypus pichiy: (Azara says Latitude between (35°-36°.) —

148b verso

The double Arg: Calc: white bed is seen single. at San Josè. — ; Non-occurrence of Shells owing to Gypsum?— state cases

Uniformity & extent of Porph. gravel bed is so modern formation. —

Tertiary formation of Patagonia not in Basin as supposed by Lyell to be generally the case but Attached to the Andes

In Bengal. (Mouth of Ganges). red clay. with Calc. Concretion (Kuncaer Kunkaer?) (Mastodons bones??) — Mem: La. Plata!. —

in connection with present few banks & necessarily small epoch since the shells. — Andes line. South Part.. Brazil. gneiss red Clay: —

Age of Pat: bed. with respect to Europe can only be ascertained by relative proportion of recent shells. — This rests on the supposition. that species become extinct in same ratios over the whole world Now. the Porph bed seems or rather the Arg beds seems to have destroyed them suddenly: though in the South allowing partial re-appearances: if not destroyed highly injurious.

such a cause would acting for such an extent must produce great & sudden alterations. —

Mem: Report of Geolog: Paraguay Sandstone is said to be a Tertiary Molasse (?) (Nature? & Authority?) if so. continuation R. Negro. — Mendozan beds: —

Where the Salinas. grandes are. West of Ventana. does not Falkner there are Spiny bushes? if so. Sandstone. —

There is a probability from. Mastodons bones. in the low cliff, which I think must have been under water. when the three hundred was above that the Mastodon has lived within a period. in which shells. have not lost their color

B. Blanca.— Animal & (Megatherium?) prove same thing

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