RECORD: Darwin, C. R. Geological diary: Lima. (7.1835) CUL-DAR37.688-703 Transcribed by Kees Rookmaaker, edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed by Kees Rookmaaker, edited by John van Wyhe 10.2012-3.2013. RN1

NOTE: This document, part of the largest scientific document composed by Darwin during the voyage of the Beagle, is written mostly in ink. Where pencil was used instead this is noted in the textual notes. 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.


688

1835 July 21. (1) Lima. —

The Isl. of San Lorenzo & the lesser one of the Fronton run NW & SE; they are entirely composed of stratified rocks; have a general dip of about 25° to SW, but beside this there are many points, as seen in the Escarpement of doom-shaped strata, & other irregularities. — The strata attain a thicknss of perhaps 800 ft, & the highest land. from 1000 to 1200 ft (aestimate). 1282 Capt. Wickes. — Guasco. Salt at Arica, Freyers paper.

The main rock is a dusky coloured hard siliceous sandstone, which has been extensively quarried. — The strata are generally very thin & the whole very regular & smooth. — The coarse sandstone is found on the lower parts of the escarpement 3135 36; most the beds are separated from each other by thin pale coloured indurated shales. which in nature resembles mudstone the substance 3145. which I have called clay-sandstone mudstone, only here hardened, in it are nodules of an inclinated clay. slate, very hard & compact 3147. 3147

Above one mass of the hard siliceous sandstone, there are strata of aluminous sandstone (3139) 3139, which again is succeeded by a yellow sandy sandstone & this again a pale semi indurate shale (3137) which contains a some concretionary imperfect strata of dark red very heavy & ferruginous aluminous laminated stone (3138) 3138. —

In these strata & chiefly in the [illeg] (3139) & yellow soft sandstone there are numerous thin layers of salt (b); & indeed nearly all the softer sandstones & shales contain some. — The hard sandstones are also separated by layers of various much indurated & altered shales, passing into the nature of jaspery or Porcelain rocks of dark green & blueish color. (3140: 41: 43) 3140: 41: 43

There are other masses of yellow broken stone (3146) 3146 & of a greenish aluminous sandstone with layers of soap-stone? — 3144

688 verso

(a) The Morro solar is similarly constituted & being connected by some breakers belongs to same line of elevation. —

(B) I am told by Mr Gill1 who has superintended the Quarries, that salt is found in all parts; that some of the layers are nearly 2 feet inches thick. — We can scarcely believe otherwise that these ha strata have been deposited in the open ocean: There has been no [preditoneum] to accumulate at its bottom, a briny fluid. —

On the outer parts of Island. layers of black glossy coal are found. — Amongst in which are vegetable pieces in the compact form of stems of some vegetable in the state of Charcoal.

I hear also of Limestone, but not in quantity, in different parts of the Island. — Moreover in the Shale there are vegetable impressions. —

All the above is oral information but without doubt correct. — Also of much Iron Pyrite, of which I saw a little. — NB It must be remembered that besides Iquique, Arica & Cobiya here, it is found at Huaca & other spots near coast of Pacifick in immense quantities. The difficulties of understanding its deposition is much increased.

1 Mr Gill was a civil engineer and architect based at Lima in 1835.

689

1835 (2) Lima

There was one remarkable stratum of a soft very ferruginous stone, (3148) containing numerous layers of salt, some of Gypsum, & lines of regular crystals of black ([illeg] faces dodecahedrons) of some ferruginous mineral.

I also noticed these crystals but smaller in thin lines in a rotten stone. — Generally the strata of sandstone are divided by thin layers of a shattered, thinly laminated, hard, brittle, pale-colored or purple shale. — & this is found in every stage till we have the Porcelain rocks. —

There are veins of quartz rock with cryst. drusy cavities & others of cryst. carb of Lime. — Above a mass of strata, constituted as thus described, we have a quantity 3142 of thinly laminated, very siliceous sandstone (or rather granular Quartz Rock).

Some of the strata are thicker, more compact & yellowish. The first kind is remarkable in many parts in having a very thin external coat, which has weathered, as black. as coal. — Some parts are honeycombed. — Again we have much true. purplish (3149) 3149 sandstone, which is capped by the hard siliceous sandstone, such as the lowest strata (3135). —

In the lower part of the Island. I found one extensive mass, of a greenish grey. feldspathic rock (3150) 3150.; on a large scale it was quite conformable to the superincumbent strata; so that for some time I was in doubt whether it was a Lava. — it was traversed by the same veins & faults. — I soon found entangled fragments of the upper rocks, & likewise lumps of the igneous rock injected amidst the sedimentary strata. — The alteration of the latter was very considerable. — passing into those varieties, which I have called semi-Porcelain stones. — (3151) 3151 is a specimen containing cryst close from junction which although in spots was almost blended was generally quite distinct. — I should suppose a bed of such igneous rocks probably extends under a great part of Island & has given rise to the alteration visible in

689 verso

(a) There was also a stratum of compact very calcareous sandstone.

See Daubuisson on salt vol II p. 394 & 51

Mem. the straw like Helictites bits of white friable cones in Shropshire
see my notes

Feb. Letter from Lieut Freyer addressed to Lyell on elevation of west coast of S. America. Geol. Proc. February 18352

Specimen at Geolog Soc. from Cerro de Pasco from M [Ricardo]

My theory of salt A. 163

[Separate sheet of paper attached to 689 verso]

Discussion on common salt with bituminous wood. — Vol. II. p. 143. 146 & Vol. III p. 231
Beudant4

1 Aubuisson 1819.

2 Freyer 1835.

3 Notebook A, p. 16e.

4 Beudant 1822.

690

1835 3 Lima — S. Lorenzo

the sandstone & shales. — In a projecting point of the Plutonic Rock, I found it curiously infiltered with hard white salt, apparently fresh fracture showed in interstices this substance — but it was not equally distributed. As this so soluble a substance is known to overlie the mass. we must believe it infiltered, otherwise I should have imagined it to have been melted together. —

I could find no organic remains. — I think it most probable, although the sandstones are here very predominant, that these strata belong to the age of the gypseous or super gypseous of Copiapo & saliferous ones of Iquique. —

Near to Lima (at the Calera) there is much hard black stratified rock, which is more or less calcareous; some is pure black Limestone, the strata are separated by shaly varieties: other parts are greyer & siliceous. — These strata dip to the East & towards a mass of crystalline hills. — They form a mere fringe at the base of injected green crystalline feldspathic rocks, which pass into greenstones. — The prevailing rocks in this vicinity are syenites, granites & I believe syenitic greenstone. —

The band of mountain thus constituted, correspond to the general coast line of such rocks in Chili. — From conservation with Dn. Mariano Rivero & his paper on Cerro Pasco in Memorial &c.

690 verso

D. Rivero has sent to London & Paris specimens & sections of in a section from S. Callao. to East foot of Cordilleras. —

691

1835 4 Lima

Ciencias Naturales; it appears that on the Granites there reposes [illeg] blackish hardened slate, with little mica. Quartz ones & Pyrites (which in one case in close proximity to granite appears converted in a green feldspathic compact rock & greenstone)

(2°). Red sandstones, alternating with red & green Porphyries (which sometimes have brecciated structure), also with white & blue. conchiferous Limestone, white sandstone, & quartz, & black shale & conglomerate. — In these beds are numerous layers of Coal. & on East side of Cordilleras Gypsum. — Here are [illeg] many of the rich silver mines. — These saliferous strata of S. Lorenzo appear closely to agree with the upper ones of this formation at Pasco:

Hence salt. gypsum & coal are belong to same formation. — & my conjecture concerning correspondence of S. Lorenzo with Iquique & these with Copiapo becomes more probable. — So far there appears a general resemblance with the formations of Chili. —

But above the 2d there comes white Limestone 3d. covered by Trachytic Granite & Red Porphyry. —

691 verso

(a) I saw specimens of a white Tosca (precisely resembling that of Coquimbo) [illeg] with shells from [illeg] near Payta (north of Lima): 14 leagues inland. —

Mr Harris sent some shells from Chira & Amatape two neighbouring places to Dr Lynen Berlin 15-24 leagues from Payta. — height supposed to be 1000 ft. —

See Galapagos notebook, p. 24a.

692

1835 5) Lima (5

In the Isd: of San Lorenzo on the NE side (a), the strata of hard siliceous sandstones crop out & form a steep slope. vide section —

In the lower part of this, there are in places two or three narrow & inclines steps. These from a distance cannot be discerned, but when standing on one of them, they are sufficiently clear. — The lowest terrace is covered in parts for the length of a mile with beds of recent shells. —

I was informed they are found in two other different places in the Island. — The highest point, where they are in numbers, was is 85 ft (Barom: measurement) above high water mark, from this they are plentiful on a slope to the edge of a low irregular precipice, which here forms the coast — The bed is level, is in parts upwards of 2 ft thick, but generally less: the shells are packed together without any stratification, & either mixed with a little

692 verso

[sketch]

1200 ft
170 ft
85 ft
Section of San Lorenzo

693

1835 (6 Lima 6

earth & broken fragments. (a) — They are frequently covered by a few inches of looses detritus but rest on mass of angular fragments, of the inferior rocks cemented together by salt & (I believe Carb of Lime). interstices of shells with salt. X (b) v. note —

The shells are of many sorts & all sizes mingled together 2158 2159; they are such as might be accumulated at the present day: the only difference, which I noticed, is the preponderant number of the Crepidulae, which is not common on the beach. — The shells are much weathered brittle & bleached; a few Turbos & a now conical little Tusserella retained the purplish & red colors. — It was curious to observe, in some of the Concholepas, how both the inner & outer surface had been removed & thinned causing the chambers of the minute (Balanidae) to appear as apertures.

Several of the Univalves had clearly lain untenanted at the bottom of the sea; small Balanidae & Serpulae were are adhaering to the inner surface. —

693 verso

(a) In the interstices between & hollows of the shells there is a considerable quantity of pure crystalline salt. — This probably was collected when the surface was within reach of the spray. — or an alluvial action from the saliferous sandstone — in either case from the dryness of the climate it would not be redissolved. —

(b) I am not sure this is universal: the fragments of course are not perfectly angular, but nearly so & not like pebbles. —

694

1835 Lima (7

Together with the shells there were birds bones bits of roots of sea weeds, corallines. — ovules of [molluscan] animals, heads & flower of Indian corn. — other vegetable matter, & lastly a piece of a rotten cotton string & another of woven rush. such as I have seen taken from the Huacas ( or Burial grounds of the Indians).

This however only proves, they might be older (but not that they are) older of an age, anterior to the arrival of the Spaniards. —

From the immense quantities of the shells alone (the bed being at least 50 yards wide), without considering their state, & position on a step-formed terrace &c &c, it is certain these have been left by the sea, when it formerly occupied a higher level. — We know then that the land has risen at least 85 ft within the epoch of existence of Man. —

There is some difficulty in imagining the manner

694 verso [blank]

695

1835 Lima (8.

in which the beds of shells were accumulated. On The existing beaches are generally sand shells & with the line of tidal action, covered with pebbles; Here the is a difference, & we must seek for other analogies. —

Would not littoral shells accumulate & angular fragments lie collected, when the sea is so deep as to be beyond tidal action. [sketch] A such as at (A). — How then have we substances which are float? — Might they not sink, when long soaked in water? — Or was the disturbed when brought within tidal action & these substances added? — Many different conjectures might be formed, but they are all unimportant. —

The climate of Peru, must be particularly favourable to the preservation of any substance, yet these shells. only elevated 85 ft above the sea. have an appearance of much greater age, than those in Chili. at a height from 2 to 400 ft. — Have then the elevations been here less energetic?

695 verso [blank]

696

1835 Lima 9

or have there been subsequent subsidences?

The state of decomposition of the shells varies to a certain extent; in some spots (& the highest) the greater part of the mass consists of small fragments, mixed with & partially reduced into a yellowish-white, soft earth. 3156 —

On the second "step" 95 ft above the first or 170 ft above the sea, beneath about four inches of loose earth there is a layer of the same fine soft white powder. 3157 — This often has a saline taste & slightly effervesces with acids. — The layer is generally a few inches thick, but varys much; it lies on a slightly hardened fragmentary mass; in the interstices of which the substance has frequently percolated. — I could not detect the most minute fragment of a shell. — But from the perfect identity of circumstances, I do not hesitate to attribute it to the perfect decomposition of a bed of shells. — Therefore the time required to raise the additional

696 verso [blank]

697

1835 Lima 10

95 ft has destroyed every trace of structure we may also presume that when the 85 foot terrace reaches the height of 170 ft there will be no signs of shells. —

Above this 2d step, there is a third with some of the white powder & indeed in many of the higher parts of the Island, even nearly to its summit 1200 ft high. — In any other climate, where rain would dissolve, remove & blend & vegetation blacken this substance, such signs of the former residence of the ocean would not remain so long. —

Yet it may afford in other cases a clue to such observations & to me, it has always been a desideratum to know what would ultimately become of similar masses of shells. —

I paid a visit to the site of old Callao destroyed by the earthquake & great wave of 1747. — The state of ruin is more complete than that of Talcuana. — The foundations alone can be discovered & over there much coarse shingle is scattered. —

697 verso [blank]

698

1835 Lima 11

The form of the land certainly has changed since the foundation of the town. — no one would have dreamt voluntarily of choosing so narrow a strip of land. — The sea to this day is encroaching on both sides & the level of the land, is the lowest possible, so as not to be overflooded.

It is protected by large high beach of shingle from the outer sea. — Occasionally salt water ouzes through it. — Yet we have no certain evidence of a subsidence. (a) — When the water, is still, it is said that near the beach ruins can be seen at the bottom. — Mr Gill (an architect) informs me it is his belief that there are only large, but loose fragments. — Certainly I saw masses of Brickwork. from 3 to 4 ft square, but on the beach & not near to the ruins of any building: they appeared to me to have been carried back back to seaward by the reflex wave. — They reminded me of fragments of rocks, at the foot of mountains. — The wave which destroyed the town is said to have

698 verso

(a) I believe however such has happened although probably to a very trifling amount. —

699

1835 Lima 12

come up from the South, or where open sea. — It inundated the level country to distance I should think of 1/2 a mile from the Beach.

There is a tradition, that the Isd of Fronton & S. Lorenzo were once joined & that the channel from the mainland was so narrow, that cattle used to swim over. I am inclined to believe there may be some truth in this, from the fact, that there are Foxes on these Islands. — From Freziers map. it is clear such changes must have been long prior to the earthquake of 47. —

From enquiries I made, I could not hear of any change in relative level of land & water now in progress. —

The city of Lima is 500 ft above Callao; the rise is however so very gradual that Humboldt quotes it as a remarkable instance of deception.1

the plain in its upper parts consists of irregularly stratified shingle. — Near Lima, it is extensive & very level; it is irrigated by more than one distinct stream — surrounds or

1 Humboldt 1819-1829.

699 verso [blank]

700

1835 Lima 13

contains groups of hills, like Islands. — I have no doubt of its marine origins, but I was not fortunate to observe anything in the form of the land at the Barros de Pagios, &c. to which Mr Cruikshanks refers. — I noticed however on one hill some pebbles, which could not have been place there by running water. — Lyell 3d Vol: 1

To seaward of Bellavista, a village between Lima & Callao there is an extensive section onto in a cliff about 100 ft high of the lower part of this plain. — Here near the beach, the junction of the low ground of Callao with a higher part is effected by an obscure escarpement in place of a gradual ascent as on the road to Lima. — The plain beyond the escarpement appears perfectly horizontal. it does however rise from about 70 to 120 ft & then again gradually falls a little. — this can alone be discovered from the heights in the sea — cliffs. —

The section exposes a number of thin strata

1 'Mr. A. Cruckshanks' reported by Lyell 1830-3, vol. 3, p. 130 to have found sea pebbles 200m above sea level at Callao. Darwin referred to Cruckshanks in South America (p. 51) as providing yet more excellent evidence of dramatic elevation, some of it in historical times (see introduction to the Copiapo Notebook)

700 verso [blank]

701

1835 Lima 14

of yellowish & red clays & fine, slightly agglutinated sand. (a) — neither sand or clays are at all pure; they alternate & blend together repeatedly. —

The strata are in places waving & thin out & replace each other. — There are layers of small irregular calcareous concretions. — Where the cliff is highest, in the middle, there is a mass about 40 ft thick of coarse granitic shingle, interstratified in curves with thin layers of the fine sediments. — Above the stratified impure clay, there is a superficial bed, on an average 3 ft thick of compact fine earth or mud: in this & on the surface, there are many pieces of broken, marine shells, together with quantities of broken earthen ware. All the latter consists of small bits of a red coarse pottery, & which from their curvature have belonged to thin & large vessels. —

These abound mostly in spots, as if a waggon full had been there broken, but are distributed, together with the shells in all parts.

701 verso

(a) some thin layers of the clay are of a singularly bright color. —

702

1835 Lima 15

In the mud very rarely there was a pebble as large as a cricket ball, but not infrequently irregular short layers of little pebbles as large as shot or bullets. — The upper surface of the plain is quite level: the thickness of the covering is not uniform: in the highest part (120 ft) it could not be less than 6 ft & these contained a few of the earthenware fragments. — I examined between 2 & 3 miles of the cliffs & about half a mile inland. — as the above part is the highest of the cliff I cannot doubt, but what the covering extends much further. probably to the limit of the cliffs towards Ahorillos, about 8 miles in length:

At the foot of the slope, which joins this plain with the lower one of Callao, a point of the clays is furrowed, & covered by a mass of mud with shells &c as above, but I suspect of a distinct age: anyhow there are signs of two such distinct coverings at this lower lever, in the uppermost one of

702 verso

[sketch]

Sea-Beach

[sketch]

703

1835. Lima 16

which, I saw a horses tooth & dogs jaw. — These may perhaps be owing to the wave of 47. — When I considered the level surface, extent & obscure traces of horizontal deposition in the covering of the upper plain. I first believed that a debacle had carried the mud &c into the adjoining shoal sea. — At however a right rectangular point, where a ravine descended to the coast, V there was a section of a pavement, formed by two rows of large cobbles stones, lying on a couple of inches of sand, beneath which were the clays & covered by above it three ft of the mud. —

Hence it is certain the inferior strata existed as dry land. — Could a wave, during an earthquake, deposit such quantities of mud, over so large an extent & so evenly? — Did it enter a Laguna? Or did the land for a short period subside beneath the level of the ocean & subsequently as at Lorenzo rise to its present height? I rather incline to this view. —

However this may be explained, there is a certain degree of interest in so great a commotion within the "recent" period. — In the great Huacas, near Bellavista, I saw small pieces. of the very same kind of coarse red Pottery, as in the mud, accidentally included in the small alcoves. — To account for their presence in such quantities & absence of other remains in the mud, we may either suppose (a), that on

[text does not continue in this item]

703 verso

(a) the plain there were Huacas containing as usual Jars which were washed down. — or more probably that there were pits in the inferior coarse red clay & kilns to burn the Pottery manufactured from it.

I incline to this opinion, because it well accounts for the to numbers in particular spots; & that, in the Huacas the earthen ware is generally fine grained, made with care & frequently painted. —

NB. Humboldt Vol. II P 227 quotes from Acosta. Hist Nat. de las Indias. an account of earthquake which destroyed Callao in 1586 AD. The wave rose to the height of 84 ft. — This do no doubt would have inundated a part of the plain. But yet I cannot think that the described appearance could be produced by a devastating wave of immense violence. —1

Read Acosta

Possibly from Ulloa of rise N. of Lima. R.N. p. 1052

As the feldspathic rocks only low down on S. Lorenzo perhaps no pebbles when sea stood higher, wind drift away sand. — lower surface fractured by earthquakes.

Land crabs do not occur here.

Se (Earth quake wave)

Mention that no earthquake Callao not pool of water

1 Humboldt 1819-1829, vol. 2.

2 Red notebook, p. 105.


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