RECORD: Darwin, C. R. Geological diary: E. Coast of T. del Fuego. (5-6.1834) CUL-DAR34.157-176 Transcribed by Kees Rookmaaker, edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed by Kees Rookmaaker, corrections and editing by John van Wyhe, corrections by Gordon Chancellor 4.2011. RN2

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.

The period of the voyage covered by this document is May and June 1834 There are a few notes dated December 1834, as well as later insertions. Page 158 (bis) is a table with elevations of different parts, which may have been inserted later. This period is covered in the Beagle Diary pp. 453-454 and South America chapter 5. Folio 169 mentions Lyell's queries about boulders and there are discussions of animal distribution near the end of the document.

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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.


157

1834 E. coast of T. del Fuego (1)

On entering the Straits of Magellan the first high-land which is met with is that of C. Gregory. This is estimated at 1000 or 1200 feet elevation, it forms a plain: which with some interruptions extends to the north of Coy Harbour &c & bends round to the East of FitzRoy Channel, (where it is called Beagle hills): from thence, it is continued on the North of Skyring water, forming there also elevated downs. — We have seen that the great 840 plain of S. Cruz extends down to near Coy inlet; where to the Gallegos a lower step continues the formation. — I think it cannot be doubted that all the above ranges, belong to the elevated series of plains: its greater elevation near to the mountain chain is what might be expected. — To the South of the Gallegos there are some high flat-topped hills the Friars &c (& perhaps. M. Aymond belongs to the class protected by the Asses ears, rocks of a harder nature), which evidently are outlyers & thus connect the formation. —

The neck of land which connects Brunswick Peninsula to the main is low, about the same level, with the land bordering the Straits. — To the South of it the country rises, & forms a flat hill which reaches to near to fresh-water Bay. (called Brecknock hill on the Otway water side). it is literally thickly covered with wood. — it is estimated at 1200 ft (or more); on the opposite coast, commencing at C. Monmouth. there is a similar range of land running in NE. direction; it is much less thickly wooded; at its NE

157 verso

(a) Mount Aymond is above 1010 feet high, which is alone an argument that it is outlyer of the high plain

r measurement. —

158

1834 E. coast of T. del Fuego — (2)

end. S. of C. Orange, it is much lower but yet retains an elevation of 607 ft. —

Stet.

When sailing to Port Famine, I clearly saw in break on the sides, that both these ranges are composed of some white, earthy substance. Before this I imagined they was were an uncommonly level range of slate.

Capt. King (a) states in his "Direct" that on the surface of the C. Gregory plain, great masses of primitive rocks were lying; this is what might expected from what we have seen in the S. Cruz, in those ranges plains furthest in the interior. — It is probably owing to this detritus & to the increased dampness of the climate, that the presence of trees, a character so universally absent in the great Patagonian formation is to be attributed. — There is perhaps something in the proximity of the slate mountains & their dense forests; a constant succession of seeds would thus be present: we have seen to the North, that the spiny bushes of the dry shingle bed, extends some few miles on the Tosca plain, & here we see the same Beeches taking possession of the former formation. —

To the South of the low land which connects Useless & Sebastian Bays again we have high land (950 ft) of the same character; it is continued behind C. Penas & Ines. appearing 1000 feet high, is very horizontal in the "Table of Onzea" 970 ft & perhaps forms the N. & S. Brothers (close to Bay of St. Polycarp) of the respective

158 verso

(a) It is not at all necessary that these plains should be formed of the same materials we have seen at the coast cliffs to the North: most probably they resemble the detritus-looking tip beds, which were found in the lower parts, of the sections near to the Cordilleras up the river of S. Cruz: (hence it perhaps comes that the recent beds on the East coast, so much resemble the ones alluded to in as much as they result from the degradation of similar ones. — ). —

158A

[sketch] B B B D D (C)
65° NW by W
A

Fig 1

(B) The yellow sandy clay ((B))

(D) Blackish fine sandy clay

Gregory Bay
May 1834

158A (bis)

does he know of any low cliffs

Antonio Sierra   1700
Anchor Stock hill   57
S.r Barranca. R.Negro   200
Brother North } Patagonia ??? ?del Rey 1640
South 1397
Belem Point. B. of St. Matt: between P. St. Antonio & Rio Negro   300
Cala Chica: 20 miles SW of New Bay   200
Cliff. North. Engano B: 25 miles   40
S. do (6 miles long)   60
Delfin P. 10 & 12 S. B. Chimpat   270
Delgado P. SE. Point of New Bay. Peninsula   200
Direction hill   564
Double hill. St. Sebastian   290
Eventes P all same. Delgado   225
Elizabeth S.   150
Esperitu Santo   182
High cliffs South of do:   250
Fort. B. of St >at: Perhaps higher ones, standing very separate. unquestionale plain   380
Green Hill. New Bay. Plain ton   220
Gap S. of Port Desire. W. of Bird Island: & SW of 350 [illeg] hill   590
Hermanas. dos: R. Negro   220
M. Hermoso   120
Cliffs to N.W of R. Joseph. 2 to 300 feet aestimate

158A (bis) verso

Lobo bc 20 or 30 S of Malaspina  
Marques Point. Middle of Bay. Plain   580
[Nereso] gulf. 1st cliff inside S entrance Pt   262
2d: (Plain perhaps 250 & 300 in [Stokes]   175
[Mirafas] Point. King says plain at New Bay less than 100 243
Nuevo P. 200
Nipple Hill. P.St.Antonio   600
C. Negro (St. of Magellan)   160
Narrow. 1st. cliffs S. side Selamanca P. 700 120
Orange. Peak   210
High land S. of do (end of C. Monmouth?)   607
Orozco. South table. — yes Patagonia   970
Possession C. (?)   320
St. Julian low point estimated 90 ft.  
Rosas Bay 20 miles W. of R. Negro. Sandstone   225
South Cape. B. of St. George: ? rounded grassy hill   250
[illeg] Sandy ridge. Pampas (Wednesday hill 120)   130
Sugar-loaf C. 3 Points. 40 miles to N. of P. Desire. Plains same height   250
Sisters false — 15 miles W. of R. Negro, continuation of S. Barranca   220
Salamanca peak   700
Sebastian C. T. del F. Cliffs   190
— Bay. 9 Hill. — (Monmouth Patagonia formation   950
Table Hill. Engano Bay. — 12 miles. cliff   350
Tilly roads. N. cliff   576
Waters edge. S do Mar 8 miles C. Marques   583
Town peak   200
White Hill. B. of St. Mark. Cliff 1 mile N. of Fort. St Antonio   300
W. Creek. peak 30-40 miles. N of Malaspina
Plain cliff ? N B. 20 miles N of [illeg] Hill of Gulf & St George.
  330

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1834 E. coast of T. del Fuego (3)

heights of 1640. 1397 ft. It is corroboration of all this land belonging to the great Patagonian formation, that we find. all about C. Ines an abundance of the yellow St. Julian. Porph. pebble — G{

When all the foregoing tracts of land, first began to emerge from the sea, that we must suppose that from previous submarine furrows there were broard channels. where we now have straits & lines of low land. —

If the land was now submerged 1500. feet. the greater part of the outside islands. would be submarine rocks & reefs; the Atlantic & Pacific would be close to each other; the channels of communication greaters the currents, & consequent waste more powerful. —

The main communications were probably in two direct NE & SW lines. — Through strong water, in a line where the narrows now are; & from Useless Bay to that of St. Sebastian hence results the NE trend of the C. Monmouth range. — Fresh elevations took place; the climate & the large arms of the sea. would cause much degradation on the sides of the soft "Patagonian" beds; the detritus however would probably be swept far away. — At length from the upheaval of the hard tocks of the West, the channels would become narrowed. some would be closed, depositions would take place in the direction of the probable prevailing currents & these probably were as now from West to East:

Such submarine strata, resulting chiefly from

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160

1834 E. coast of T. del Fuego (4)

from the wear & tear of the "great Patagonian beds, would by fresh elevations be raised into dry land. — Such I believe has been the origin of all the lower land, which extends from North of C. Virgins to near Port St. Polycarp. (a distance of about 200 miles) & of that which lies between the C. Gregory & Monmouth ranges. — The land of this formation is generally uneven, this perhaps is owing to local circumstances, such as being exposed to strong currents during elevations; for at C. Virgins it is tolerably level. —

Its height of course ranges proportionally: 200 150 to 250 (angular measurements) will include all which certainly belongs to this class. —

I will begin at the northern point & so describe it down the coast. —

Boulder N. of St of Magellan

We anchored near to C. Virgins, I did not go on shore, but saw a good series of specimens: The cliffs are tolerably even, their altitude 170 feet; they entered about 18 miles up the coast & are separated from the R. Gallegos by a tract of low country:

The prevailing stone is a yellow, very soft fine-grained, clayey, laminated sandstone 2056; the laminae are generally very numerous & remarkably even & straight. — (I never saw a roofing slate with more even parallel planes of division). —

With this there are interfolding beds of blackish indurated mud 2057, containing very many small angular fragments of slate & some low rounded blocks of syenite & greenstone of the size of a mans fist to his head: —

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161

1834 E. coast of T. del Fuego (5)

These beds were of various thicknesses, some 20 feet: they occurred in no regular order sometimes; generally there were three or four of them, & horizontally stratified; in other cases waving with the two ends thinning out.

The surface of the plain differed from those we have seen to the North, in there being but little shingle & rather more vegetation. (a) — Gr.

Entering the Sts of Magellan. — The cliffs on each side of the first narrows are of a whitish color & appear of same nature with the last described ones. — On S. side 120 ft. high

Gregory Bay1

At Gregory Bay not far from the foot of the great C. Gregory range there are some low cliffs chiefly composed of the blackish undurated mud, as before. —

The fragments were both angular & rolled they were chiefly of slate & syenite; some of greenstone, hornblende rock, serpentine, feldspathic rocks & conglomerate; in size from a walnut to a turnip, occasionally rather larger; in some places without any planes of divisions; in others interstratified with masses of yellow clayey sandstone; with lines of large pebbles; with curved plates of fine gravel. — Two sections from the structure of the cleavage much interested me: in one (Fig 1) blackish sandy clay, very finely & much laminated; was interstratified, with a yellow, more sandy clay, also much laminated & the laminae more straighter & more even; these beds dipped at the high angle of 65° to the NW by W. — The difference of color, straightness of line of separation & its high inclination rendered

1 The Beagle first anchored in Gregory Bay on 12 February 1834 (Beagle Diary, p. 423). KR

161 verso

(a) Hence perhaps it comes, that it is frequented by many Indians. — whose horses could not hunt over the plains of shingle. —

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1834 E. coast of T. del Fuego (6)

this very curious, & immediately brought to mind the cleavage of the old clay-slates:

The chief part of the cliff (25 feet high at this spot) was composed of the yellow sandy clay; on the right hand it contained some large pebbles & lost all signs of cleavage:

The black clay in the upper part, became most curiously convoluted & mingled with the surrounding substance: at (c) I have drawn these curvatures as carefully as I could, but the regularity & the manner method in which one layer was folded within another is not at all well represented; some of the curvatures were very acute: — As before, I was strongly reminded of those slates, which often having layers of quartz, are contorted in every possible manner. — At Maldonado I compared them to Gothic windows, one within another. — I should have mentioned that in the blackish clay, where the main layers were fre straight, the more minute ones were twisted. (I have represented this in one layer, but far too coarsely, as it could be perceived in a hand specimen)

In the lower part there is a regular anticlinal line in the blackish clay. —

I could trace the laminae to the very apex of the triangle. — Many other sections &c show violence is here out of the questions: how then did current. separate & incline two substances at an angle of 65°. — How did they produce the curvatures & anticlinal. laters:

162 verso [blank]

163

1834. E. coast of T. del Fuego (7)

Gregory Bay.

(Fig. 2.) shows a main bed (F) about 18 inches thick & 30 feet long, with other minor ones, composed of yellowish very sandy clay which lies in a coarses sort. One end of this bed dips at small angle to the South, the other is bent & twisted back on itself. (as represented). — This did not fail to call to mind the somewhat similarly curved beds of quartz rock at the Falklands. — In the main bed (F) I counted 20 small basin=shaped =stratiform masses; about a foot wide; from being placed at pretty regular intervals, they resembled ornaments round a building. — Beyond the curve there were others, but not nearly so regular. —

I noticed on the beach of this bay & in other parts of the Straits that the pebbles were entirely of T. del Fuego origin; quite distinct from the Patagonian bed of shingle; yet situated close to it: Gr

As I have said, we find such patagonian pebbles on the outside coast, this is what might be expected, from the constant currents which must have swept through the great valley between the Monmouth & Gregory high ranges. —

2d Narrows

The cliffs on the west side (N.S. Gracia) are about 160 feet high; they are generally consist of of a whitish sandy clay (or clayey sandstone) here & there may be seen a curling layer of gravel; it is studded irregularly with pebbles from the size of a walnut 1815 or smaller to a man's head,

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164

1834 E. coast of T. del Fuego (8)

2d Narrows

some angular, some quite rounded. They are (& generally whenever I mention pebbles) of the same rocks already mentioned described. —

In the upper parts, where there is most stone I saw one block four feet in diameter. I noticed here, but more especially in some other localities, the occurrence of large sized pebbles in very fine sand, laminated sand. I was at first puzzled how the two could occur, together, but it is clear, currents, such as have deposited the layers of gravel, have dropped them, the smaller ones being removed at the time or afterwards & then the fine sandstone formed round the boulder. (a) — On the ground, above these cliffs, there were Limpets & Muscles, retaining their color, as so often described on the plains of Patagonia. —

At "Sweepstakes Foreland" on the opposite coast the cliffs are of same color & nature, but appear rather finer & more laminated. —

Elizabeth Isd

The cliffs are 150 ft. high; they are composed of whitish sandy clay (or rather whitish earth) contain many semi-rolled pieces of slate. Hornblende rock & Syenite &c &c; few larger than a mans hand & not arranged in the slightest order. Above however such a mass, there would be a layer of gravel & then another mass, without any signs of regular deposition: generally the upper parts show most signs of the latter effect. —

Although there are no large boulders in the cliff, yet at its base there were many of

164 verso

(a) I omitted to state, that at the foot of the cliff some large boulders were lying: one of quartz rock. mean height 1ft 8in. mean girth 15 ft, irregularly square: — (I intend by the expression "mean" that a regular figure bounded by such sides, would be of equal bulk with the one describing[)]

Another rounded oval, mean. H. 1ft 3in same circumference. — There were half this size & many quarter. — The subject will be presently discussed. —

165

1834 E. coast of T. del Fuego (9)

Elizabeth Island

greenstone & syenite, from two to four feet in diameter: at C. Negro. however there was a very large one, which had evidently but lately fallen down. — When standing on Elizabeth Isd with C. Ne & looking at C. Negro. behind you; & in front the Islands of Martha. Magdalen & Sweepstakes foreland; all about the same height, appearance & nature; the conviction came very strong to the mind that they had once formed a continuous plain. —

C. Negro

Cliffs. 160 ft: very white earth, with interfolding layers of gravel. — Hence strong resemblance with C. Virgins. — The narrow neck of land, which separates the straits from Otway water is apparently of same nature, as all the above: it like the side of straits has been much water-worn & now presents a very uneven surface. — The line of the old channel seems marked by "shoal harbour: & the NE trend of Elizabeth Isd. —

Shoal harbor is remarkable from the vast numbers of enormous blocks, which project 6 & 12 feet above the water, & are of angular shapes. (not perfectly rounded). —

Before returning to the outside coast, I may remark that generally the beds within the (old) straits are much coarser & contain larger fragments than those on the outside; & this is what might be expected. —

A.C. Esperitu Santo, there are high cliffs, 250 ft: white & brown horizontal, with some waving ones at as at C. Virgins. —

165 verso

Say N. of C. Virgins certainly Boulder formation. S. of it doubtful

V. first pages for facts about Patagonian founders entering T.del Fuego

166

1834 E. coast of T. del Fuego (10)

St. Sebastian Bay

I landed on the SE side; the cliffs must be between 300 & rather more than 200 feet high: the earthy sandstone is more or less pure 1847, it contains a few small pebbles; in some places there are beds of gravel. There were lines of concretions, almost forming an entire layer of hard sandstone. 1848 — The former stone was often divided into laminae & by a great number of the leaves of trees; I believe they are from the Beech which now so abounds on the mountain; there was also much many pieces of wood: there were present also horizontal layers, containing a very few shells 1847 ,,, 1851. There were chiefly a Pholas; which seemed to be in their proper position, one was encrusted by a Balanus & this by Flustra, which seems to have retained its color. — there were also some fragments of Turritellae & Venus & a crab. — Before I considered the nature of these remains, when I recollected how very nearly the mineralogical character of the beds agreed with those most inferior ones. high up the S. Cruz. I doubted whether they might only be the lower part of that formation & not a more recent formation one. The organic remains are by no means sufficient to decide the question: but upon reflecting on the appearance & state of these remains, contrasted with those of Patagonia I can have no doubt on the subject. — It must be recollected, that on the former supposition these beds must have been formed, in sea probably at least 1500 feet deep; now, I shall presently show, the cleavage seems owing to

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167

1834 E. coast of T. del Fuego (11)

St Sebastian Bay

currents. — these such may be doubted to occur at such a depth: it may also be questioned, how far Pholas. Balanus. Cancer would flourish in such a site; & again how so many leaves & wood could be sunk so deep. —

On the contrary, the appearances are to me, those which would occur in a bay where muddy sand & leaves. brought down by brooks might collect, be deposited, & often times be removed & altered by currents. — The layers of sandstone were slightly curvilinear & generally inclined; but no two sections of 20 yards remained the same. — a common dip to the S. ∠20°. —

the upper beds which are more ferruginous, have repeatedly cut away & replaced the lower with basin shaped strata. —I have represented one section on the other page (a): they overlie some horizontal beds. — On the plains, behind the cliffs there were some muscles. yet retaining their bright blue color. —

On the SE. side of the bay (& therefore protected from the most violent weather) there were many immense blocks of syenite & other western rocks; one was oblong, with a roof like a barn; its mean height 5 feet above sand, (& probably many feet below it) had a girth of 47 feet: there were several others of half & 2/3 of this great size. —

The cliffs here contained nothing larger than gravel; it is therefore highly improbable they were washed from out of the sandstone. —

167 verso

(a) [sketch]

sandstone more ferruginous
more inclined
∠ 20°. —

168

1834 E. coast of T. del Fuego (12)

South of this Bay I did not land, but the ship sailed pretty close to the shore. —

There were many cliffs. I could perceive no material difference in their nature; perhaps the lines of we strata were, when present, more generally horizontal. To the North of Port St. Polycarp they entirely ceased. —

In the geology of Tierra del F: (P 100) I have described some beds under the name of Alluvium: These The cliffs in the Beagle Channel precisely resembled in appearance the foregoing ones; their estimated height is 200 ft; taking this into consideration, & the nature of the pebbles, & the proximity of two basins, no doubt can be felt of their contemporaneous deposition & elevation. —

The cliffs which fringe Navarin Isd &c are lowe, perhaps formed in a deeper sea & where I examined them, consisted of a mass of rounded & angular fragments imbedded in a blackish earthy clay; some of them were of a large size: the whole cliff much resembled those within the Straits, where there are no lines of deposition. — In both places I have felt considerable doubt, how far under ordinary circumstances, such substances of such different figures & sizes. could be placed together & no lines of division, owing either to intervals of time or difference of specific gravity be present.

If we bring into play the successive elevations (shown on the coast of Patagonia) we must recollect, that these were horizontal or concentric with surface of the ocean; now the only effect, which I should imagine, would ensure

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169

1834 E. coast of T. del Fuego (13)

from one of these, would be a rush of water, bearing probably with it much detritus, from every opening of the inland waters towards the sea. — Much of the pebbles we have seen in the cliffs come from rocks on the western coast, where the channels are both much more numerous & deeper. — How them have could such currents bring these rocks to the East shore. —

These rushes would probably clear out the channels, where perhaps, from the action of constant tides & currents materials from the West had been collected. — Hence perhaps the amorphous state of the deposit. — But this subject is intimately connected with the transportation of boulders, to which I turned my attention, from some queries sent by Mr Lyell to Capt. FitzRoy. —

I have alluded to their occurrence in several localities: the two places, where they most abound & are of the greatest size is St. Sebastian bay. & Shoal Harbor. & these are unquestionably the mouths are of ancient channels, previous to some of the last elevations: In the other places & about Navarin Isd it may be supposed, that the collection of Boulders at the foot of the cliff is, owing to their being washed out of it, & remaining long after the earth, in which they were imbedded had been removed. — This I do not think applies to the immense ones in St Sebastian Bay. — I think so the more from seeing on the line of coast N & S. of Port Famine great Boulders. — These I will describe. In a very sheltered little cove, north of P. St. Anna, (the

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170

1834 E. coast of T. del Fuego (14)

tides, in this part of the Straits rise from 7 to 9 feet & have no great power). I noticed some blocks of that peculiar granite, which occur in the NW arm of the Beagle Channel, (where the mica is replaced by (chlorite?)). one had a mean height of 3 ft. — irregularly circular girth 15 ft: another of white syenite (another common western rock) was 11 ft in girth & 2..6 in height. — Another of conglomerate; generally there were few in these coves. — At the foot of M. Tarn there were many boulders of western rock at the top of high-water mark: one of hornblende (a) had its corners rounded, mean height 4ft..6, girth 24 ft. — an irregular-pentagon, there were many half, & quarter & less than this size. The parent rocks of these does do not occur in the range at the foot of which they lie. — The question is, have these Boulders been carried by the action of ordinary tides & currents, or by sudden rushes of water, caused by elevations of the land (perhaps in the latter case being transported in a mass of detritus). —

On the other Against the first hypothesis we have the angular (points only rounded) form of the blocks, if they had been rolled along during a succession of years, we should expect to see them like Boulders, in the central parts of England, with no one salient [corner]: Also, general arguments against the transporting power of water, by itself; drawn from such rivers as S. Cruz.

170 verso

(a) A mile or two north of "rocky point" I noticed one large block of the a rock. like (1995) it stood. 3 4. inch above the sand; & 18 in girth; rather oval flat topped, there was another of a feldspathic rock much larger, but much buried. —

Shape generally. rounded = angular, but perhaps this results from a tendency to an angular fracture. —

June

What I have said about their being found at top if high water mark, must be taken with great latitude

171

1834 E. coast of T. del Fuego (15)

where the stream runs 5 & 6 knots & where there are no eddies or lakes to detain any large stones. Although the tide in the narrows runs at a far greater rate, yet this by no means is the case in the other parts of the Straits. — The power of the sea, during strong winds, in such narrow winding, deep channels can be but little.

For this side of the question, we have the fact, that their exact position seems determined by the line of high water. —

Against the other side, I have already specified my greatest difficulty in not seeing how the rush of water should bring fragments from the West shore. — It is clear my data are insufficient to come to any satisfactory conclusions. —

Against both these Hypotheses (a), there is a very startling difficulty; it is the great depth of some of these channels: — SW of Freshwater bay & [blank] miles from the shore there is no bottom with 690 feet; only about a mile from P. St Anna. the bottom is 660 feet. — East of C. Froward, in midchannel, there was no soundings with 1536 feet; now this is the very high road for the western rocks to travel to the East. — In Christmas Sound Capt. Cook had no bottom with 798 feet.

These great inequalities must be from original form. therefore they would be so much the greater previous to all every elevation. ؟ Must we suppose, these boulders, coasted along

171 verso

(a) Since writing this I have revisited Port Famine: I see there is a low plain (perhaps 60 feet) not composed of fragments &c. now this probably was formed at bottom of sea & elevated with the rest of the country. — I find that the Blocks of western rock are not confined to the beach but are scattered for 40 & 60 feet on the hill sides (I should not be surprised if the rounded outline of M. Phillip (1308 ft) points out the a covering or entire structure of alluvium). —

All the blocks in the sheltered coves, without doubt come from the alluvium on the sides of the hills. — so that the question is reduced to the manner how blocks were scattered over the C. Gregory plains & those high up the R. of S.Cruz. — The difficulty from the abysses remains the same. — Also the greater numbers in the old channels, I think can only be explained by there having been the exits for a long period of ordinary tides or extraordinary debacles. — generally however the Boulders may be attributed to the alluvium. —

Decemb: 1834

؟ The quantity of strata removed in these old wide channels & heaped up on the former beaches, may account for this appearance: ? Even if the elevations were not quite concentric; as they are hardly it seems very doubtful if their effect would be great.

Mr Playfair (P 408)1 seems to consider the Boulders in Europe to have traveled on the sloping land, before the intervening valleys had been formed. In this case he would say, before the Straits & Channels had been scooped out by the tides;

But then the great depth in certain spots (& not on East part) where tides are most rapid, show these have not been thus hollowed out, but that the irregularities are original; a consideration (which is strengthened by such facts, as the presence of numerous islands or a broken sea, being a certain consequence of a greenstone formation. ؟ Have the depressions been caused by the (V. 16 (a)

1 Playfair 1822, p. 408:

The constant agitation of the waters, and the declivity of the bottom, are no doubt the causes of this gradual and widely extended deposition. A soft mass of alluvial deposit, having its pores filled with water, and being subject to the vibrations of a superincumbent fluid, will yield to the pressure of that fluid on the side of the least resistance, that is, on the side toward the sea, and thus will be gradually extended more and more over the bottom. This will happen not only to the finer parts of the detritus, but even to the grosser, such as sand and gravel. For suppose that a body of gravel rests on a plane somewhat inclined, at the same time that it is covered with water to a considerable depth, that water being subject not only to moderate reciprocations, but also to such violent agitation as we see occasionally communicated to the waters of the ocean; the gravel, being rendered lighter by its immersion in the water, and on that account more moveable, will, when the undulations are considerable, be alternately heaved up and let down again. Now, at each time that it is heaved up, however small the space may be, it must be somewhat accelerated in its descent, and will hardly settle on the same point where it rested before. Thus it will gain a little ground at each undulation, and will slowly make its way towards the depths of the ocean, or to the lowest situation it can reach.

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1834 E. coast of T. del Fuego (16)

this shore, avoiding the deep abysses, as a Scylla or Charybdis, but that many thousand, have fallen into them? ؟ Must we suppose that for every boulder which has accidentally traveled East-ward, hundred have been carried by the rush of retiring waters into the Pacific? — The number of blocks, which these conjectures require is to me as nothing, having seen the mass of enormous fragments which at the S. Cruz have been washed from the Cordilleras. —

The chief points of interest in this east crust; are firstly; it being a very recent sections of the oceans bottom, probably precisely similar to what we should now see if an elevation was to take place. —

At the present day almost every sort of bottom contains some sort of organic beings — shingle — muddy shingle & even sand for on the fragments of shells corallines &c grow. — From not seeing such in the beds, I imagine the formation be very slow, so that every trace of an animal is decomposed before the layer is concluded, &c that they only have been retained, where the deposits have taken place more rapidly. — 2d. the transition from local circumstances, which we now see, from a mass of earth with great pebbles & boulders to a fine laminated sandstone, with calcareo-sandstone connections. — 3d. — the curious forms of the cleavage & its common occurrence & resemblance to the old rocks. — But with this very wide difference, that there is not that remarkable uniformity which we recognise in those rocks. —

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(a) Note to page (15)

reverse of a point of upheaval (?) Looking at the chart, rocks boulders of the outer coast would most easily arrive at the East coast of Brunswick Peninsula (P. Famine &c &c) from due South. But then this is the very line in which we meet the great pool.

Can we imagine, that when the Sts of Magellan were at a higher level & more open, the common NW gales compelled stones to travel along the coast to C. Froward, from which point the southerly gales (the two most common points) would send them to the northward to P. Famine. —

At present I am much inclined to believe all fragments traveled with detritus & this was a debacle, owing to the larger elevations of the land, causing a retreating wave ??? ——

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1834 E. coast of T. del Fuego (17)

4th. — The exact resemblance to some of the most inferior beds, in the great Patagonian Formation of so much anterior date seen up the S. Cruz; which is what might be expected, as they result probably from the wear & tear of somewhat similar beds, increased by the detritus of similar mountains. —

We have seen the general height of this formation is about 200 to 250, it is therefore probable it rose, when the 250 plain last elevation took place; or it might be contemporaneous with the 350, the sea being rather deeper in these exposed southern parts. — The shells on its surface prove, what otherwise would be almost certain, that it did not rise very much before the 350 plain. —

In the Beagle Channel & in the Sts of Magellan the appearances were strong in favor of the land on each having been joined (especially presence of Island of same elevation as sides in mid channel)

In the former we showed the presence of some animals, which do not exist in those Islands, where this formation does not occur. —

In the low country on the East coast, I have found two others, which from their feeble weakness & subterranean habits would be very unlikely to swim across; there are the Toco Toco, & the mouse (or Gerbillus with grooved teeth) (978 spirits): now these animals are quite characteristic of the Patagonian plains & occur all along the North coast of the Sts. — To me these facts are convincing of the former connexion. — there are however many difficulties in imagining a

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1834 E. coast of T. del Fuego 18

channel elevated into dry land & as many in imagining it to be reopened. — We have given reason for supposing the Channel has existed from the first. — Also in Patagonia that there was no very great elevation but probably that some one exceeded 100 ft. —

Now the channels at the present day are deep in some places 3 & 400 feet as in the narrows (a): generally perhaps a line of 130 ft: Formerly they must have been greater & probably deeper. — Hence the difficulty in imagining how the an ordinary upheaval would connect the two sides. — We see it however in the Peninsula of Otway Water & Useless Bay. —

[there is an illegible sentence in the margin]

Some such hypothesis as the following will perhaps most easily reconcile these difficulties: there were then, two main parallel channels, through Otway Water & Useless Bay, so that the present n N & S. part of the Sts by Magdalen Isd &c was shallow: elevation taking place & choking up the channels in the mountains caused the northern one to become shallow & finally dry land. & with it the shoal part near Elizabeth Isd Magdalen. Martha &: Here then the animals passed over. — Perhaps The water was left in the narrows & other deep parts & certainly in the very deep part of the Straits N of Freshwater Bay. There would then be two bays, consuming the cliffs, till they joined & reformed present channel.

We have proofs that the sea, even at the head of a deep Bay, does gradually wear away the cliffs. — At St Julian at the very head, there are vertical cliffs, annually falling down & being consumed. — At St Josephs & New Bay, the very

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(a) If the an elevation was not sufficient to lay parts of the bottom of a channel dry, I should think action of tides would soon eat it out to the required depth. —

Where a channel is contracted it must always be deeper; if a continent was laid dry, such as narrows would be marked by lakes, these lakes would form a chain in a valley:

Can this explain some of the chains of lakes in different parts of the world ?? —

Decemb: 1834

The migration of the animals may be accounted for by supposing Sweepstakes foreland formerly connected (as appearance now says) with Elizabeth island & mainland; & that the a channel of passed to the East of it, which from lowness of land undoubtedly did happen. —

When the channel from Otway Harbor dried up, animals reached Sweepstake Isd & after this the supposed peninsula being broken through (which actually seems to have happened). The main stream of tide left the its former channel to the East of the Sweepstake & this became dry, but low ground, by which animals passed over to T. del Fuego. —

The very form of in the chart renders it probable there would be a peninsula point ending in Sweepstake, between the two channels, one from Otway water & the other from the South passing to the East of the Foreland &joining in the present bay between the two narrows. —

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1834 E. coast of T. del Fuego (19)

question in point seems to be in the way of slowly being decided; the neck of the land, (9 miles wide) 4 & 1/2 wide cliffs in New Bay extensive which the separates the two Bays is fronted on each side by cliffs. — Where these occur. I think the land must always be in the act of suffering degradation. — It is probable in such large Bays, the matter gained by the tides is distributed over the bottom, but when once a channel, this shallow bottom of course would be furrowed with a channel. —

[sketch]

When two bays meet & form a channel. it must always be by two large curves cutting each other;

If we suppose the junction of the two waters to have taken place any where else, excepting near Elizabeth Isd; the form of the two narrows & the enclosed bay will offer great difficulties: no two Bays endeavouring to meet could cut such a channel, as there exists. —

To finish with the hypothesis, after the animals had passed over & the channel reopened (b) (b) fresh elevations raised the land to its present position; separated by a tract of low land. Useless & St. Sebastian Bay & settle the course of tides, which has finally impressed the present form on the land.

With respect to the formations in the neighbourhead of the Beagle Channel; the case is more simple; we now see, that the ocean has left only strips or vestiges of the once probably continuous beds; hence we must imagine then an elevation took place sufficient to raise U into land, the intervals between the islands & that since then the sea. has simply removed such land. — We have here no such curious

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(b) Leaving Islands & banks & peni points. —

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1834. E. coast of T. del Fuego (20) (or 166)

forms of land, as we see at the narrows in the Sts of Magellan. to cause puzzles & hypotheses. —


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Citation: John van Wyhe, editor. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

File last updated 22 March, 2013