RECORD: Darwin, C. R. Geological diary: Elevation of Patagonia. (5.1834) CUL-DAR34.40-60 Transcribed by Kees Rookmaaker, edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed by Kees Rookmaaker, corrected and edited by John van Wyhe 2-3.2011, 11.2012. RN3

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.

Sandra Herbert discussed this essay in Herbert. 1991. Charles Darwin as a prospective geological author. British Journal for the History of Science 24: 159-192, pp. 174-181.

Compare Darwin's discussion of the elevation of the plains of Patagonia with his illustration in Journal of researches, p. 202 and Darwin's detailed treatment in South America. Note also Darwin's notes on a conversation with Captain FitzRoy on the final folio (page).

Editorial symbols used in the transcription:
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Text in small red font is a hyperlink or notes added by the editors.

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.


40

(1)

All used except Theory of [gradual] plains p. 8

Elevation of Patagonia

There is discussion on Valleys in Valparaiso paper

These are some preliminary observations before we consider the actual facts respecting the elevation of these the southern plains of T. del Fuego, Patagonia & La Plata. — (a) We shall show these plains have attained their present elevation by more upheavals (subsidence of seas) or than one: how far can we expect to find evidence of this fact / that evidence rests on finding a succession of plains. Where the sea has a tendency of we throwing up materials to increase the dry land. — the red appearance form of the new land after many elevations would be a gradual slope in the form line of elev former deepest water with lines of beaches & sand-dunes, somewhat following the same curves as the present sea. —

if on the other hand by the action of currents, the sea cut away carried away the loose materials near the beach, cliffs would must be formed & the land of whatever thickness, would will gradually be diminished. — On The principle effects of this in a coast which has is well shown in Lyell Vol III P1 [blank] is to remove evidence of successive elevations. —

(consult Whewells paper on tides & currents).2 — The greater part of the coast from C. St. Diego to C. Corrientes is bounded by cliffs. — this is alone are evidence of which a proof is now taking place. — that the sea is here a destroying element. — the form of the coast shows the same thing. — Looking at chart, we see it consists of a series of differently sized curves. — Now I believe the [hornises] of or extremities of all these curves alone, consist of hard rock, we may

1 Lyell 1830-3, vol. 3.

2 Whewell 1833.

All used except Theory of [gradual] plains p. 8] insertion written over other entries on the page, 'All used' encircled.

40 verso

From the evidence drawn alone from these plains I do not know any proof that the land has risen in preference to the sea having subsided. — As a fall in the altitude would necessarily affect the seas of the whole world. — I think we may feel certain that no catastrophe has been so violent as to cause any great & a sudden subsidence of such as 100 feet. — Reason will be given for supposing that one set of plain was elevated at one period more than the number of feet. —

Of course the weightiest argument against the hypothesis of fall of sea is simply that it is more improbable; it requires a greater amount of change. —

The removal of cliff of 800 ft height most certain proof of power of water

Mr Conrad on North American elevations must be studied1

R.N 452
p. 46-49 most important
p. 67

Examine charts of Patagonia
proportion of cliff to low coast & for nature of soundings

Plans of coast

R.N. i 69
Channels in rock on Costorphine hills

No faults in Patagonia, if lowered again as quietly, who would even believe beds conglomerate had once formed surface

only emit over fluid!
could so [illeg]

Terrace at New Zealand, at Antipodes

On the theory on solid rocks corroded
[Glide] R.N. 93 to 95
R N p 38 and 53
Vide New Zealand 1 1 (a)3

1 Conrad 1835.

2 Red notebook, p. 43 (Darwin's page 45). The many further references to the Red notebook pages are not given as notes but may be seen by following this link and scrolling up or down for the page in question.

3 A reference to Geological diary: Bay of Islands, New Zealand. (12.1835) CUL-DAR37.802-811.

41

(2)

hence infer that the whole line of coast, was gradually being consumed untill that certain points of hard rock protected certain points, but then after this the intermediate spaces land continuing to be fall a [furlong] to the sea. the present curves were formed:

Penguin Isd (S. of P. Desire) & C. St Diego forms one the horns of one great curve. these points are both rock, one slate, the other Porphyry. — Within this C. Virgins is the most projecting headland, there are good reasons for supposing the shoal which lies off it is composed of rock: the bottom is very uneven; & from the mark on the lead, these must be large angular fragments if not solid rock & the direction of the shoal is the usual line of the rocks of the country, lastly the productions which came up with the Clams were such as I had no where else seen, on the coast: small curvatures may be noticed between penguin Isd. Spiring Bay. Watchmans C. & C. lookout all points of Porphyry.

From Penguin Isd to C. Blanco. the coast is generally faced with rock & hence pretty straight. — From Between C. Blanco — composed of quartz to C. two Bays, where there are islands of porphyry is the curve on Gulf of St. george. — For many miles north of this the coast is pretty straight & the points are all rocky:

Off the Peninsula of S. Joseph (the Bays of St. Joseph. & here are to me quite inexplicable). the Spanish charts lay, down rocks & certains the bottom is very uneven. — This point. with the hard sandstones of the R. Negro. perhaps from the Bay of St. Mathias.

C. Corrientes is rock. to the North this the

[Note many of the places named by Darwin can be found on the chart of South America published in Narrative 1, here.]

41 verso

{During a period hypothetical of subsidence. shingle, would remain understratified with sediment}

Speculate on extension Leaward of a Plain near S. Cruz: compare to denud of Lias as in Shropshire

41A

100 ft plains

Measurement in Escarpment

250 ft plain from P. Desire to N. Bay of St. George = 170 miles & probably same. Rio Negro BB clam about new

330 to 350 ft Gallegos. S. Cruz. between St. Julian — perhaps at N Julian

at P. Desire. at C. Blanco — at N. Cape of George Bay (& little S. of New Bay is probably wall of probably off St Joseph) = to 8 1/2 degrees = say 500 miles accurate

580. Jilly - Bird Isl. 590 - say about 200

Gallegos to Coy 350. S. Cruz. S. sea 355 N. side. 330. Bird Isd. 350. P. Desire 330. extending for my count. — N. Gen P 330. Falk Land bay 350 S. of new Bay

N of S. Julian plain 2 or 300

Plain sort of Coy. 200 to 300. — Port Desire 245 to 255. C. Blanco 250. north George 250. S. of New Bay 200 to 220. — North of St Joseph plain 200 & 300. —

Plains about 220 Rio many 200 at 200. — Bahia Blanca 200 to 300.

Bird Isd 500 — great Plain within 590. —

100 ft Plain 90 St Julian — Port Desire 100: — 100 mile apart — All about St. Joseph Bay & New Bay.

41A verso

lower plains about Bahia Blanca
stages
90-100 (1)
220 to 255. (2)
330 to 350 — per (3)
580 to 590 (4)
710 5
840. (6)
950 (7)
other at sea (7 yards) (?)
1200. estimate (9) 8 — at least 8. =

52
39
13
60
780

39
52

90 100
250
350
580
710
840
950
P. [illeg] & St. Cruz

42

(3)

the great band of sand-dunes show the sea is not gaining on the land. — Many of these points & curves must be modified by the action of currents — I think however their first origin is to be attributed to the cause pointed out. —

The plains to the eye appears absolutely level & no where are there signs of violence in the configuration of the strata. — Granting that it is more probable that the land has been elevated, then the sea subsided; it is necessary to consider in what manner the force has acted. — Either the upheaval has taken place in a plane concentric with the form of the globe (or ocean); or a gentle inclination there may have been given from any a line or point of violence, from which these districts, appearing to the eye level, may gradually slope. — On the latter supposition no one can doubt that. that the it is owing to the line of the Andes. — Now I shall show that in ascending the river of S. Cruz, the plains do rise in height, & we have seen at St. Josephs. there is a most small dip to the East. Yet all this would certainly occur on the first supposition of an elevation concentric with the surface of the ocean. — It is clear that the formations of Patagonia are owing to matter procured proceeding from the great chain of mountains of the Andes. (Lava. pebbles superior & inferior. Gypsum. white aluminous beds &c)

42 verso

(4c) [blank]

43

(4)

(a)

My data for judging It is first necessary to judge if the inclination of the tilting of the former sea. My data are exceeding scanty. —

Taking the line of soundings from the Falklands to S. Cruz & excepting the portion near the coast we have shown the inclination to be 1": 22'. —

This will give in a distance 137 miles, (a number chosen with respect to station up the river of S. Cruz) an increase of depth of only 54 Fathoms, 83 miles gives 33 Fath: 65 miles 25. — Now this certainly is less than what generally occurs on the coast of Patagonia. — for instance I see from various soundings that at a distance of 60 to 80 miles, the common depth is between 50 & 60 Fathom; but in the line specified from S. Cruz we have at that distance this depth at nearly above 100 miles from the coast. —

This greater shoalness is perhaps owing to the presence of the Falkland Isd. — I have not data enough to get another angle of inclination. —

It At the distance of 137 miles we may however feel pretty sure, that the ancient sea had a greater increase of depth than 54 fathoms, perhaps if we assume from 80 to 100 it will not be too much. — I think it not improbable

43 verso

(4b)

that when the sea washed the bold Eastern of side of the Cordilleras the bottom would shoal more suddenly than it does at present from the lower coast of Patagonia. — at least such generally is the case. —

From 160 miles the distance from mountains to some head of submer the Andes to seas — would was certainly should have at least 100 fathom inclination. —

44

(4c)

The result however of my examination of the heights of the plain up the valley is not satisfactory. — I had not means to obtain sufficient data. — The only inclination of the plains. (was in the second series. called in "Valley of S Cruz" D & Dn) was from the in 24 miles to W of noon cliffs on 25th in which there was a rise of 185 ft; giving for the whole distance from the mountains to sea. — (160 miles) 1233 ft. — which is more than double what would be expected as explained (Page 4a & b). — But this observation & the following one is rendered doubtful by Lava occurring in the above interval, & it is not possible to know what effect this would have on slope & bottom bed of sea. — On the other hand, on the other hand the highest plain which (not a very regular one) which I measured, is 97 miles from coast & 1416 ft high. Now this is only 516 ft higher than the 900 plains on coast (assumed 900 between 840 & 950); accordingly as 160 miles gives 100 fathoms :: 97 miles gives 363 ft. — So that these plains are only 153 ft abo higher than would be expected with a concentric elevation. — An estimated height (with good reasons) of another one plain of the highest series gives the same result. —

Hence we may feel pretty sure, that if there is a dip from the line of the Andes. it is very small, only 100 or 200 ft in a hundred miles. — the facts mentioned in Valley of S. Cruz seem to render some dip necessary.

The angle of a dip of even 300 ft in 100 miles is only 1':42"

44 verso [blank]

45

(4)

These beds, when forming the bottom of the atlantic, would necessarily slope from the shore or beach at the foot of the line of hills. — Hence, if whatever inclination they then possessed, they would retain if elevated concentrically with the form of the globe: The only method For instance, if any part of the bottom 100 fathoms deep was should be raised by one or more elevation into dry land above the level of the sea. — the beach, from which the bottom gradually inclined, would attain a height of 100 fathoms. — & the intermediate land a gradual slope. —

The only method of ascertaining, whether how much of the present state of these plains is owing to the latter cause of to a tilt how much to a tilt from the Andes, is to compare the increased height of the plains in the interior between at any one two point, with the probable slope of the oceans bottom in the same distance. —

If, (as it appears to me) the slope is made sufficient might well be imagined to have been sufficient to cause the increments of height, the hypothetical tilt, which must have been excessively small & which cannot, as in the other case, be shown to exist in degree, may be entirely banished. — The probable actual amount of this slope will subsequently be discussed is here attached.

From my geological notes, it will be seen, that recent shells [mostly] retaining their color have been found, on various series of plains from 400 feet. downwards. in a space composed between. St Sebastian & S. Joseph, the distance of this coast line

45 verso [blank]

46

5)

being nearly 800 miles. — We may hence certainly infer that these such plains have been elevated from beneath the sea within the period, which shells exposed to atmospherical changes could partially retain their color & animal nature. — I can feel t no doubt, but that the space is much greater; the similarity of nature & height in formation S. of Beagle Channel (I never landed in the most likely parts so did not find any shells). renders the contemporaneous elevation almost certain. — in the same manner there can be no reason for supposing that the plains north of St Joseph of a great height extending by the R. Negro. — to the neighbourhead of B. Blanca were elevated anteriorly to the great extent of S. coast. — With respect to the lower plains of the Pampas the same negative reasons may be applied, together with also the fact that the bones found above the oyster formation in one of the lowest series of plains, belonged in all probability to an animal which lived subsequently to the elevation of the higher series of plains with recent shells: & this animal I believe to contemporaneous with be one of those (or anyhow coexisted with them) whose bones characterize the tosca of the Pampas, & if so the improbability is very great that they the Pampas were elevated anteriorly, to the southern plains, which was dry land. — Counting only from the northern point, where I have seen the tosca (& I hear know it extends much further) this gives the immense space. of 1600-1700 miles

46 verso

(a) Two reasons preclude an expectation of finding modern shells on the surface of the Pampas: the murkness of the vegetation, which would in a very few years conceal & decompose shells; in fact & 2d the probable conjecture, that the tosca is a deposit of in a great aestuary in an old R. Plata; on which hence marine shells would be absent or scarce. — In On the surface of few countries, excepting on dry, sterile plains of gravel such as in Patagonia could it be expected to find shells, which would not in a few years be utterly be decomposed & much less retain their color. —

Mem. Chili !!! Half dry. Half year rather wet

But not much vegetation

Old coast at M. Video above La Vacas

47

(6

(6)

idem in one direction

equal from London to sea of Azof), which has been uplifted [illeg in margin] the period alluded to. — With respect to the other direction or breadth I am necessarily quite nearly ignorant. —

x) If on some future day I shall be able to prove that the West coast has been elevated to a dozen within the same period. — it will almost render it certain that the whole S. part of continent has then been elevated. =

About 140 to the W. miles up the S. Cruz (elevation above 200 400 feet) there were some modern shells retaining their color

= at least the 400 feet & in the period alluded to. — I have said that such I have found such shells on the 400 ft plains & down-wards — but I by no means, not think it is clear, that they would not be found on some of the higher series: my opportunities for examining such have been exceedingly few: the reason is a because; as will be shown much they generally lie as far from the coast.

Besides the about approximations to a general age of degree of contemporaneous elevation; a much closer one may be pointed, when, it appears. Besides the above approximations to the date the upheaval of the whole set of lower plains: it appears taking the height for an index, that several successive steps in the series, can be shown in different parts. of the coast widely removed from each other to be of success contemporaneous elevation. — Which if frequent rendered favourable will give a high idea of the extreme regularity with which the

47 verso

(a). — The places, where I found shells are as following.

Cliffs of St Joseph. — Ostracae (height 100 ft?) these were Patellae. — Mytella. Buccanum & Balani, not partly imbedded in sandy earth. —

At Port Desire 2 Mytili & patellae abundantly on the 250 plain. especially in the heads of some little valleys, others were lying quite exposed on the plain. on the 330 plain & 4 or 5 miles from the nearest sea. —

At P. St. Julian on the [90] ft. plain. abundant:

at S. Cruz: —quite exposed on plains & c 2 mytili & Patellae on the 350 plain, 5 miles from the sea. Patellae & Voluta at an elevation of nearly 400 ft. — & particularly buried in soil

At the furthest highest point of the S. Cruz. river, which we reached, the elevation must have been between 3 & 4oo ft. & distance. 140 miles from the sea. Atlantic & on the beach were Patella & Voluta. —

At St. Sebastian on cliffs more than 200 ft. — Mytili on the surface

at P. N. S. Gracia. 160 ft. protected by earth. —

The mytili in all cases more or less retained their color. — & occasionally some of the other shells. —

The officers state, shells are found P. St. Antonio

It is to be observed. the above places, were the only ones, which I visited on coast of Patagonia —

48

7)

subterranean force has acted. —

Beginning at S. Cruz. — a point, where I had the best opportunity of observing these facts, I will collect what describe as far as I am able respecting the present position of the plains of Patagonia. — The cliffs below to the South of the anchorage are 355 ft. high; Both by ∠ & Barometrical measurement on ascending to the edge of these the eye roams over, an apparently horizontal plain, without any one inequality. — To the SW at about 6 miles distance there is a line a level line of an escarpement stretching across the country. — I walked in a SW by S. 30° W direction to the Eastern point, of this range: the plain, although appearing so level I found at the foot of the escarpement 108. feet higher than on its edge the 463 feet; the greater part however of this 108 ft rise was in the last 1/2 mile.

The edge of the escarpement is 710 ft high. — When on the top I found this only to be 463/247 the a small plain or fringe round a greater one of 840 feet. —

This latter plain extends to within a mile 710/200 (or rather more) of the outside beach of the outside sea: the slope is broken & irregular, & no one could trace, with any certainty steps, such as the foregoing plains; — There can be no doubt, that the 710 escarpement formed a beach from the when 350 plain was the bottom of the sea. —

48 verso [blank]

49

8)

((Theory of Plains))

The Escarpement slopes gradually so very evenly, because alluvial action on a hill side has removed the line of tidal influence on the beach. — The place I fixed for my measurement I believe to have been too low. — But assuming it as exact, in this former sea we should had at a distance of six miles a depth of 108 feet, or 18 fathom. Now at the present day, this would be about the depth, which might be expected at the same distance. — In a like manner, we always see, the sounding deepen much more rapidly close in shore, than at a greater distance; hence the increased slope at foot of escarpement. — it is very interesting thus finding the bottom of the ocean with its shells with all its usual forms, converted into an elevated plain. — The slope is in this case in a N. 30 E direction; it is superfluous here, even to state how manifestly there is no connection between it & a line of upheaval of Andes. — I have stated that in the 6 miles of plain which slopes: 100 ft there is no ridge or any sort of inequality; it becomes a question of considerable interest, whether this puts extent of the oceans bottoms rose at one movement: if there was more than one upheaval, of course there must have been a corresponding number

49 verso [blank]

50 9)

of beaches cutting the line of inclination: — how the under any circumstances a beach, must form a sudden slope of several feet; but on this part of the coast the tide at the syzigal periods rises 40 feet; as the coast must, of at the former period has had so nearly a similar configuration that I see no reason why they should then have been much less. — on this supposition the a beach would form, as at present, an great high ridge of shingle. — The smallest ridge on these plains would last for about very many ages: — The alluvial action, from the nature of the climate is so small, that the rainwater generally collects in shallow-pools & is never only drained off. ways by evaporation. — from these facts it appears to me certain that one elevation (( perhaps counting was at least 108 feet. — I say at least because, the lower measurement begins at the edge of a cliff, which has been & is diminishing: it is impossible to know how far the slope, without a ridge, was continued. — If I had not measured & twice walked over this plain, I should have been inclined to attribute the present state of the plains to a succession of small elevations, such as occur at Chili. —

50 verso

(a) I do not mean it is necessary that it rose in five minutes or a day. but in so short a time that no beach — no coast-line could be formed.

Perhaps from analogy a small sudden rise is more probable. & (if granted) its returning water may (perhaps?) explain some of the valleys. —

51A

[illeg] P. 10

[sketch]

Andes
Plains of Patagonia
D C E A Sea F Sea B K G

51A verso [blank]

51

The the 355 plain & fringe of 710 plain are found within the present line of coast degradation.

I have stated that these are not seen on the outside coast, where the 840 plain forms the boundary: I shall presently show that the 350 plain by no means attained its present elevation by one movement, but that these are several subordinate plains marking the steps; taking this into consideration, the above fact is a strong instance (& in a short period of time) how completely traces of successive elevations may be lost. —

Respecting the actual modeling of the plains & the bottom of the sea. the diagram will show what I suppose takes place. — The original plate extended from the mass of beds at the bottom of the sea dipped dipped from the Andes in the line (C A K). they were covered with gravel. & after some one elevation let us suppose. the sea cut intersected the slope at (A). — after certain number of years the sea would extend to form the cliff (C D): from the beach (D) the bottom would rapidly incline as at (D E). — What inclination would it then have? —

would it degrade the whole mass of gravel &c between G & K; ? or would it not rather form a flat, or less slope, as (E F) untill it joined the original slope (A K). — By this means a flat

(P)

51 verso

(P) Considering line Z. K is representing plains of Patagonia. If the steps or elevations are not very large, it is clear any point in the new land, must be of nearly same relative height with (Z) as in the original line of the sea's bottom (Z K). — This can only hold good, where as here, no fresh depositions are added, & where the a surface of gravel, not easily transportable, is only remodelled. This process however must by attribution reduce its quantity, & perhaps to a greater degree than would at first be expected. —

During the process of elevation horizontal as well as vertical extension would in the plains take place till currents in the Atlantic gained power to remove the strata as they came near the surface of the sea & before they could be converted into land. —

This of course would also depend on the degree in size & rapidity of succession of each elevation. —

If of course there is a tilt from the Andes, of course the line ZK from every elevation will become more inclined

52

11)

would be ready formed for a fresh small elevation to raise into dry land: By this supposition, a considerable mass of gravel is removed, in water which must be in some depth of water. — I cannot reconcile this with my observation about Corallines on pebbles, off the coast. — It is clear where in forming the cliffs it is clear the softer matter is removed, the gravel of (C F) being reformed on (E F). —

Returning to the consideration of the plains, the 710 one only forms a fringe to the higher one plain; & yet I have not centre must or yet I think its origin must can only be attributed to a distinct elevation. — The 840 plain may be seen stretching for many miles down the coast; it appears perfectly horizontal (it must be remembered how imperceptible the 108 ft rise was; at P St Julian there is a 950 plain; it is possible such might occur in the very range & yet not be visible excepting where presenting an abrupt escarpement): this plain passes round the head of Coy inlet, south of which I know nothing about it: but I have no doubt it trends across the country to the high ranges by Gregory Bay & Skyring water, which are higher, because nearer to the mountain. — It will hereafter be shown, that the plain in the interior probably belongs to this series, & are only a little higher from the inclination of the bed of former sea. —

At S. Cruz the 355 ft plain abuts against & terminates towards the South of the plain. — When the valley of St. Cruz is discussed we shall see how far this can be traced up its sides. —

52 verso

The word "about" means estimation

53

(12)

From the R. Gallegos to Coy Inlet, the charts state the plains to have an elevation from 3 to 400 ft. Going northward after crossing the low land at the mouth of the S. Cruz, we again have plains of 330 ft. — Now this, without doubt is part of the 355. plain already described; & this from its being more distant from line of former beach, the sea was deeper, & hence the plain now rather lower. — This plains extends apparently without a break to the chain, which forms the South of the Harbor of St. Julian; here however the elevation is 430 ft; this rise is however to be accounted for, on the same principle viz its close proximity to the a high series (as we formerly saw the 355 plain 460 at base of 710 plain). The higher series alluded to, can hardly be called a plain, for at present there exists only truncate conical hills which also have the same elevation of 950 ft. & evidently were once connected:

What relation this plain bears to the extensive 840 one, to the South I do not know. — whether a distinct elevation or whether the same one has been acted with 110 ft more force or whether the sea was so many feet shoaler? the its present extremely worn & degraded state, can be accounted for by this land having formed a remains promontory in old sea; for the plains both to the North & South belong to the low series. — the point which forms the South entrance of the harbor is very level, its length is 7 or 8 miles & breadth 3 or 4; on the surface are an abundance of marine shells: its height is about 90 or 100 ft. —

53 verso

(a) The promontory, in all probability, was once the northern point of S. Cruz Straits. — & these high plains are perhaps connected with the inland cliffs. seen bordering the valley of St Cruz. —

54

13)

This plain I have not the slightest doubt is the index of an elevation, quite distinct from any which we have hitherto seen the traces of. — How otherwise indeed can its presence be accounted for? With the exception of this, I know no where in the Southern parts of any certain similar one belonging to the same series. — Near Bird Island 20 miles to the North we again have our old 350 plain & this joins one to a 590 plain (both ∠r measurement). — This latter plain extends down the coast close to St Julian, where, in consequence in the space of a few miles, we have the 90 ft. 430 ft. 560 ft. 950 ft four distinct plains. — I think it not at all improbable that the 590 plains. is a high one, which I saw at the head of the P. Desire Creek. —

About ex Watchmans Cape excessive denudation, has broken through entirely removed several miles of the 350 plain, at Port Desire 3 or 4 miles North of the Anchorage, we have a 330 plain. — the 25 foot diminution in height may easily be explained by the distance these plains are from any elevated series. which could form the old beach:

Between the above plain & the anchorage, there is an extensive one & quite level 250 ft. — it joins on with the higher one by an escarpement hence I conclude thus is an index of a distinct elevation. — the difference between the former dry land & sea & bottom being being only 80 feet. —

At two places, at this plain, we have a cliff behind a cliff, with a sloping bank between them: [sketch] the lower

54 verso

(x) North of Port Desire I have not myself seen the coast. & am merely able to judge of the plains by the angular measurements taken by the officers on board the schooners. —

55

14)

one, in both cases, being about 100 feet. — I attribute their origin to the same time, when the low plain at Port St Julian was formed. (some low cliffs N. At C. Three points (N. of C. Blanco) there is an extensive 250 ft plain, which stretches into the Gulf of St. George & belongs clearly to the lower one of P. Desire. In the central of this gulf, there at Tilly Roads & P. Margues 20 1/2 miles apart, there is a plain which three ∠r measurements make 580 ft & which clearly is the same as that near Bird Island. — Mr Stokes informs me when standing on this plain. & looking towards the interior several successive steps were visible & that he estimates the highest plain at 3 200 ft. — Several miles (?) 150 miles to the North behind P. Lobos the same high range may be seen; I suppose this greater elevation must be attributed to a greater degree of force or number in the earlier elevations. — The posterior later ones appear to have been constant; although the edge of the 580 plain shows no degree of succession plain yet at S. Point "S Cape" the North end of the Gulf, we have the same 250 ft plain, which we have seen at C. Three point 130 miles due South. — Again Moreover not far off at "W Creek Peak" the cliffs plains are 330 ft, the very same height within 5 feet, which my Barometer gave to the plain at P. Desire, which forms an escarpement on the 250 one. — In the neighbourhead of the R. Chupar. & New Bay. the plains seem less simple, the common I think the 350. 250 200-250 & a lower one. which perhaps either corresponds to St Julian one, or the great plain of the great

55 verso

[map]

350 ft plain
16 miles inland

New Bay
170 ft
P. Nunfas
245 ft
200
C. Chican
40 ft
R. Chupat
Engano Bay
60 ft
P. Delphin
270

56

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of the "Pampas" in the North. — The diagram shows their relative position. — At Engano Bay the 60 ft plain is 6 miles long. there are some low plains also at New bay. — All the Plains about New Bay, St Joseph & the Bay of St Mathias & R. Negro — seem to be included in about between 220 — & 240:

May 2d measurements & estimations. — The decrease in height It is difficult in this part to know to what plains in the south they correspond to the greater distance from the mountains &c would alter the depth (a) perhaps the elevating force might be different. —

At B. Blanca, I estimated the main plain at 200 ft.: at M. Hermoso there is another of 120 perhaps possibly a still lower one at P. Alta. so frequently mentioned in my geological notes about B. Blanca: the rows of inland sand dunes, rising in height these attest also several elevations. — About South of C. Correntes the cliffs were 70 ft high & pro which probably is the general height of the Pampas in that Latitude: at B. Ayres it would seem the plain is 40 ft. — but on the coast of the Parana, as far as St Fe, I estimated it at 50 ft sometimes a little more or less. but always to the eye. perfectly level. —

The tosca of these plains. abounds with bones of large quadrupeds. — it is at least a curious coincidence

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It is a curious subject conjecture only the plains of Pampas attain so little elevation? either the earlier elevating did not extend so far north or they acted with less force. or (to which I am inclined to lay great weight) the first mud, brought down by the ancient R. Plata, was deposited in a deep sea. such as this probably at one time was at the distance, the sea was here very deep being far from all land, & that only in the later periods, the first mud, brought down by the old R. Plata

(a) & if a tilt did exist from the line of Andes its ∠r fo is not known. — Therefore plains would be of rather different height according to distance from that line. —

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8
480

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finding similar bones in the covering of the 100 ft. plain of St. Julians. —

[sketch]
40 to 60 100 60 250 350 580 350 710 840 580 950؟ 350 100 1200

The plains which are drawn connected have been seen close together generally forming escarpements

From the above notes, I think we clearly prove 7 or 8 successive elevations; I have no doubt several other sets of plains might be traced if I had as one was to visited visit the whole coast & was make many measurements: Likewise it is highly probable that all traces of many elevations may have been entirely lost. — It must however be recollected the reasons, which I gave for sup believing that the ground one of movement was at least 108 feet. — I daresay many of the elevations were less powerful. — so that the number required in the 840 plain is by no means that represented by 840/1080 — As argument for this the 350 plain is more distinctly to be traced, than perhaps any other one plain: & therefore probably had an original greater extent. — This one can be traced on the coast line, at intervals, & often of great extent for a distance of 550 miles. — the 250 ft from viz the Gallegos to Engano Bay: the 250 pl. can be traced over for a greater extent; from from South Port Desire to B. Blanca. — in neither of these could do I include the modern formations of Tierra del Fuego. who the height of which is about 250 ft & which unquestionably was uplifted

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eit with one of the latter series. —

The 580 plain is found at, 2 points. situations more than 200 miles apart. — (It should be recollected that I have not picked out those height which agree with others but have used all, where they represent a plain). — The Pampas have a height of about 50 feet in a distance N & S line of at least 300 miles long. — Considering how little of the coast was examined, with geological views I think it is quite astonishing the agreement in height, up in the different series of plains. widely apart.

I feel quite convinced that the whole part plains of the modern formations of S. America from above C. horn to near B. Blanca, a distance of nearly 1200 miles rose was raised at formed by elevations, which acted over the whole of this space with nearly an equal force. — Moreover I am strongly inclined to believe that the whole tosca formation of the Pampas & B. Oriental extending upwards to the neighbourhead of Paraguay. rose at the same time with the lowest plains of the southern parts. — If my conclusion is granted (& in no other way I think can the coincidence in heights be accounted). it appears to me, that the phenomenon of the elevation of strata, is so grand so uniform in its nature, that, the explanation offered by Mr Lyell of injection of Hypogene rocks

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is quite insufficient. — Can we imagine a mass of melted matter 600 miles in length, forcing upward lifting up a great thickness of strata to almost exactly the same height? — It resembles more the gradual expansion of some central mass. — bating by intervals on the outer crust. — How far is this connected with the chain of the Andes? We know that during previous to the formation deposition of the lower strata, which was form the strata the plains. — a chain of hills existed of slate & porphyries; that during the deposition, this was a chain with active Volcanoes. (In the greater part, although in not all, these volcanoes are not now active.) Can it be connected with cessation of volcanoes. if so favourable to Mr Lyell's theory; ) the fact of the Pampas, which have certainly been elevated in a late period & which extend far to the North of several volcanoes is strongly against this fact). The elevations being concentric with form of globe (or certainly nearly so). is a strong argument in contradiction to any direct connection of the elevation of plains & mountain chain:

especially as a mountain chain did exist previous to this epoch??. Then Was the bottom of the ocean elevated from some great depth before the Tertiary strata were deposited: did this expansion of the crust of the globe cause the line of volcanoes, did they which pouring forth materials for the strata: & the expansion continuing were the pre plains elevated

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I am induced to believe. that wherever land has been upheaved in the recent period, shells will be present as evidence. — i e That shells last, even when most exposed for an exceeding long period

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in their present height. — As the chain of the tides extends whole length of S America. — this conjecture (a) require the whole of America to have begun rising about the same time; if from a deep sea, perhaps it may account for general absence of secondary formations.

As some authors have supposed the elevations of continents took place, when the agents of change were in a state of greater activity, it appears to me a fact of high interest that such a large part of this extremity of S. America, has been uplifted, in a period during which recent shells exposed to atmospherical change have retained their color & animal nature

(a) Which is now known to be the case & this is any same argument for connection between these nearly horizontal plains & chain of Andes

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Conversing with Capt: Fitz Roy, ha concerning the recent elevation of the continent he suggested the following bold hypothesis:

The number of distinct languages in T. del Fuego & the the difference of their habits from surrounding similarity in physical structure suggests an high antiquity to the race of these Indians: — It seems a most strange fact, that any power could have induced a set of men to leave the fertile immense & beautif fertile regions of temperate America & inhabit the miserable country of the South. — May we conjecture that this migration took place, anterior to the last 2 or 3000 ft elevation; when the greater part of America was to be being covered with the sea. necessity want of food might well compel small tribes to follow to the extremity the ridge of mountains? May we venture to enlarge extend this idea — the lofty plains of Mexico & Peru would form fertile regions probably existed as dry land at an immensely remote epoch. — Hence have did they not become to the two centres of civi aboriginal civilization? —


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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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