RECORD: Darwin, C. R. Geological diary: New South Wales. (1.1836) CUL-DAR38.812-836 Transcribed by Kees Rookmaaker, edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed by Kees Rookmaaker, corrections by John van Wyhe 3.2011. Corrections by Gordon Chancellor. Edited by John van Wyhe 2011-2014. RN4

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. See the Beagle diary, pp. 680ff.

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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.


cover

38

C7c (vii)

Notes on the geology of places visited during the voyage (812-960)

812

38a

January 1836 New South Wales. 1

My observations on the Geology of this colony are wholly confined to a line from the coast, passing through Sydney, & Paramatta to Bathurst. — The distance is rather more than 100 Geographical miles & the direction about W 15° N. —

I believe however this section give a good general idea of the structure of the country for some degrees both North & South of it. —

The first marked feature in the configuration of the country which is met with, is the escarpement of the Blue mountains & the River Nepean at its base. — The line of separation of the low from the high country does not appear to be accompanied by any corresponding Geological change in the rocks. — On each side a great formation of Sandstone is found. —

The land between the Nepean & the sea, does not rise above a few hundred feet in height & has an irregular outline. — The sandstone, is moderately fine grained & compact & white coloured; parts of it abound with ferruginous matter & contain layers & veins of clay Iron stone. —

The fissure consider Granite and Sandstone dissect separate & profound valley.

I observed in several plains that the superior stratum is either an indurated ferruginous Clay or a soft Clay-Slate

[in pencil in margin] M Lesson considers granite and sandstone districts separated by profound valleys

812 verso

Granitic dykes abundant in India.
[Chulu Tunlua] Dr Benza

P.M. Benza, surgeon and geologist.

813

1835

24. Inn. Travellers Rest. Mr Nixon. (good Inn)

17 Bridge on the right road leading to Dunhaved. "Penrith"

29 1/2 Do. across South Creek

32 Cross roads. Camden to Richmond. — on the left good inn — Tindales. —

33 a little further is Governor Bourke's M. Mr Wilson excellent accommodation. —

34 1/2 Emu ford. ferry Nepean river: then alluvial plains.

38 1/2 Pilgrim Inn. best

51 20 miles Hollow. Spring of water

58 1/2 Weather braced Hut (good mountain Inn): semicircular view

69 Black heath. Gardner's (said king good), a mile or two from this Govetts leap. —
The direction of road changes to NW. —

*11 descend by Mount Victoria: surrounding country vale of Clwyd ("Flanagan's House. King")

72 3/4 Point called Mount York

XXX Mr Hughes. 5 miles beyond "the Pass" Capt. King1

81 1/2 a Granite ridge ∴ a descent to Bridge a

83 3/4 Farmer's Creek ∴ The base of mountain. Trap.

84 1/2 Ascent on opposite bank of Cox? river division of the Waters. —

91 2 miles beyond this Hill: good Inn —. Prince George appears most convenient half way. station between M. Victoria & Bathurst. —

1 Philip Parker King (1791-1856), retired naval captain.

813 verso

Emerging from fine wood first view of Bathurst plains. —

Low ridge. Brown Hill. last before plains of Bathurst

open country

cross river Macquarie

Cross Queen [Charlotte'] Ponds. Settlement of Bathurst

Wolgan
Walerawang

[lower part of page]

Blackheath 3411

24 Mile Hollow 2738 ft

Weather Board Hut 2834

Foot M. Victoria at Flanagans House 2607

Ford at Cox's River 2052

Mount Blaxland (the first summit) 3040

Hill beyond Yorks' bridge 3496

The next hill in the crest of the dividing range 3496

Antonio's Creek (bridge) 3121

Fish River ford 2643

Emu Valley Creek. near Drakes Hut 2583

Summit of hill descending to Bunbringle Creek 3554

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1836 New S. Wales. 2

the laminae of which are horizontal. —

The Sandstone, as seen in the vertical cliffs nr the coast, is divided into many strata.

I noticed in many places, a pseudo stratiform structure, where the layers, inclined at an angle of 45° were included between horizontal beds. [sketch]

Where the section was not extensive, or the upper part deficient it was difficult not to believe that the strata had been so displaced by violence. — The real stratification appears to be nearly horizontal; on the coast, a small dip inland was perceptible. —

At Prospect hill the sandstone country is intermitted by a mass of Trappean rocks: the quarry which I said consisted of a black Basalt (?) 3441 the structure of which was roughly prismatic.

I imagine, but have no proof, that this substance has burst through the sandstone. — At Illawarra it is stated there is a great Trappean formation (a); the soil from which supports a most luxuriant vegetation. —

Structure Blue Mountains
escarpement

In the valley of the Nepean I first met with rounded pebbles; the masses of Shingle are found at the distance of more than a mile on each side & elevated upwards of 200 ft above

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Trap in Both. relations anterior

Form of mountains —

Escarpment pebbles

Part cause of steepness

Stratification dip seaweed

Original deposition, should have drilled had it not been edge of platform horizontal generally

evidence currents careful examination. [illeg] of alteration

Nature of rocks in escarpment patches of shale

p. 7 Rocks Blue mountains. pebbles. false stratification

Ferruginous plates

thickness uniform nature comparison sentence [illeg]

p. 10 at Wolgan carboniferous comparison with C. of Good Hope. origin of granite pap softer coal country now lowest Euritic siliceous

valley of separation. lower escarpment granite country. dikes.

[illeg] sileceous capped with coarse conglomerate.

p. 11 associate with knolls of quartz yellow cryst lamination

trappean rocks. Clay slate. state in Full.

allude to D. Fitton other case

[illeg] dip to NW.

p.13 Lockyers line spend Trachyte

p. 14 Plains of Bathurst, Nepean river

No Diluvium. interior plains free from pebbles

Summary. Older formation probably [illeg]

Lower Sandstone. of not known any age for one physical feature

Lower sandstones- [illeg][illeg][illeg] texture = ؟ carboniferous

Valleys

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1836 New S. Wales 3

the level of the river. On one side they therefore lie on the flanks of the Blue Mountains. — The parent tocks of the pebbles are not found in the immediate neighbourhead: they consist of compact siliceous sandstones & various Trap rocks. — One kind is so remarkable & pretty, that I have brought specimens. 3442 —

Have these sandstones been the ordinary ones altered by the contact of the Trap rocks? — The present river could never have placed this gravel in its present position; it belongs to the substances called Diluvium; & which in this case probably was left by the retiring sea.

The locality which I am mentioning, is at Emu ferry, & is at the present time only a few miles above the highest point of influx of the tides. —

The Blue mountains ought properly to be described as a sloping platform; the surface is irregular, but as a whole may be called level; it is divided by broard & profound valleys. — The edge of the Escarpement over the Nepean, although forming a marked feature in the country it is not lofty perhaps 6 or 700 ft. Travelling towards the interior, the slope

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18341 New S. Wales 4

is so gradual, that we are astonished to find ourselves, after riding 15 miles, at an elevation of 2834 ft. (Capt. King, Barom: Observ:), this is at the Weatherboard Hut. — Again at the Blackheath (7 miles further) the height is 3411 ft.

This is nearly at the Western limit of this great elevated platform. — The whole of this tract consists of Sandstone, which has with very trifling differences, the same constitution on the Eastern & Western sides. —

On the edge face of over the Nepean, I particularly examined the Sandstone; it is all white & rather soft; the strata only slightly vary; in some grains of transparent quartz cemented by a variable quantity of soft white aluminous powder & ferruginous matter is the essential character. 3424 3425 The rock contains some concretions & veins of Clay Iron stone & a few pebbles of white Quartz. — In some those a few places I noticed angular pieces, from 6 inches to 2 or 3 ft in dimensions of a soft clay. shale included in the Sandstone. These pieces manifestly were not fragments, brought from some preexisting rock [sketch], but the remains of strata, which currents, after their deposition, had almost entirely removed. To show how completely this had been

1 Date should be 1836.

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18341New S. Wales 5

effected. the thickness of these patches, was in one case greater than the length, at least in the one direction visible in the Section.

These pieces were by no means so abundant, as to allow the line of the former thin stratum of shale or indurated mud, to be traced. — The laminae were parallel to the stratification of the Sandstone. — I looked at this appearance with considerable interest because I had been formerly surprised at finding in the Gneiss of Rio de Janeiro, an angular fragment of very similar shape, but greater size, of mica slate.

In that case the laminae of the two rocks had a similar direction, but different inclination; the first & [illeg] mentioned
from what I have said occurs in the sandstone, this might here likewise have happened; and then if the rocks had should been metamorphosed we should might see a fragment of mica slate included in a Quartz Rock.

Besides the evidence of currents existing during deposition of the sandstone, displayed by the deposition & set subsequent almost entire removal of the slate, we also commonly see the inclined

1 Date should be 1836.

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1836 New S. Wales 6

pseudo-form structure. — In all the upper part of the escarpement, the stratification as seen on a large scale, is nearly horizontal; but on the slope, the beds dipped at a considerable angle to the East or from the platform. — At first I thought this was a case of ordinary upheaval or displacement; but on finding this these beds succeeded & almost covered by horizontal ones, I examined them more closely & found that the planes of division were scarcely ever parallel or preserved for any length the same inclination. The appearance was if the beds of sand had accumulated on a steep bank, which supposition agrees with the existence of those currents. as already proved shown to have been so active. — I do not doubt, that the escarpement has been modelled to a great degree, by the sea, when it occupied the valley of the Nepean & deposited the shingle; The river, of the Nepean itself. cannot have effected much, for although it flows for some length the escarpement of the Blue Mountain, yet a few miles to the South of Emu ferry, it obliquely enters by a narrow gorge the escarpement itself. —

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1836 New S. Wales 7

as I have said, I consider it highly probable from the form of stratification, that the form of the Blue mountains face of this elevated platform originally existed as a steep bank of sand, beneath the Ocean. —

With the exception of irregularities of this class, the strata over the whole extent are horizontal.

In many places on the Eastern side, I observed those inclined masses of beds inclined at various angles up to 50°. — The point of dip was not constant & within a very short distance, the direction would be nearly opposite. —
ferruginous veins
red clay slate
uniformity stratification thickness to 1800 ft thick
Pebbles Discussion no [illeg]

Further inland or more to the West this structure became rarer & I think in proportion to the sandstone became coarser.

Wolgan coal granite country
First formation sandstone origin crystalline specimen

In the neighbourhead of the Weatherboard, this change was every evident: the sandstone here contained quantities, being almost composed of small rounded pebbles from the size of grain to a pea or bean. — & there were a few even an inch long. — Parts of the sandstone contained much ferruginous matter, such would assume the form of thin strata layers or veins, which often pursued a very irregular course. 3426

In plains this sort of stone, was so preponderant, that the

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1836 New S. Wales 8

ordinary sandstone only remained as concretionary balls of irregular figures: — the action of the weather having removed these softer parts, masses of rock stood out honeycombed & of strange forms. — a (a)

From sections obtained observed in the profound valleys near the Weatherboard & Blackheath, I should suppose the Sandstone must be at least 2000 ft in thickness; I believe none of the strata essentially differ: I neglect such trifling exceptions as a few feet of a red clay slate at M. Victoria. —

At this last place the road leaves the platform & descends several hundred feet into the Vale of Clywd. A little way further on we first find granite, which here is of that beautiful kind, containing very large crystals of feldspar. There was also some paps of a reddish siliceous granite, containing a few elongated crystals of hornblende. — I observed the Granite, in four places traversed by dykes a few feet wide of a decomposing Greenstone. 3427

The Granite also, to the depth of many feet was in a crumbling state; but in the midst of such kinds, large sphaerical masses retained their hardness & brilliant fracture. This

820 verso

(a) I may remark, that these veins, which thus in parts form the preponderant substance of the strata, cannot owe their origin, simply to the infiltration of ferruginous matter. I have seen detached nodules, composed of the same substance, which on fracture may be were seen to contain, ordinary Sandstone. The same face. which separated the constituents of these shells or crusts, has likewise given origin to the veins, & vein-like layer. —

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1836 New S. Wales 9

sphaerico-concentric structure was also shown by the greater number of the hills being surmounted by great balls, appearing like detached boulders. — With the change of underlying rock the aspect of the vegetation immediately improved: instead of an entangled wood, the trees stood apart, allowing, as in Park scenery, a light pasture to cover the ground. —

I here made a slight detour from the direct road to Bathurst & passed through Walerawang. — I continued to ride through a Primitive country, generally having the escarpement of the sandstone, on my right hand; although I did not actually see the junction, there can be nod doubt the horizontal strata immediately impose on the crystalline rocks. —

At Walerawang, besides ordinary Granite, there was that kind, where the Mica is but very partially developed; also Euritic & Siliceous rocks, containing imbedded grains of quartz & scales of Mica. I These were encased by a Sandstone-Conglomerate, containing large more or less perfectly rounded pebbles of the adjoining hard rocks: at such strata form the base of 3 great sandstone formations. —

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1836 New S. Wales 10

The sandstone in this neighbourhead is carboniferous. At Wolgan the head of the valley of Wolgan, beneath many strata of a sandstone, composed as before of grains of quartz 3428 3429, white aluminous powder & ferruginous matter there are repeated alternations of pale Blue compact clay-slate, carbonaceous Shales. & Coal & Sandstones. — 3430 3431 3432

One layer of coal was a foot thick. — I believe the whole rested on ordinary sandstones. — In another spot, I found pale blue clay-slate with impressions of Dicotylidinous leaves & othe layers of Coal & Carbonaceous Shale. 3433 3434 There can be no doubt, but what, coal is abundant in large quantity over all this district. Although the Coal & Clay-Slate are abundant, as compared to what we have hitherto seen, yet even here they bear in proportion in mass to the Sandstone.

It is well known what large quantities of coal are procured at Newcastle & other places from this formation. So that in the Geology of Australia, this may well be called the carboniferous formation. At Illawarra (& I believe the Hunter River) large quantities of silicified wood are found; from what I can hear, these must proceed from the same sandstone strata. 3443 3444 —

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1836 New S. Wales 11

About 9 miles from Walerawang, we come to the line of watershed, dividing the sources of those rivers, whose courses are known, from those which flow into the vast interior. — The probable absolute height must be 3000 ft above the sea; but the ridge itself is scarcely perceptible, & of no elevation being merely a mound between two opposite flat-bottomed, several slightly inclined valleys. —

A few miles to the South, the line is there formed by high Granitic hills, which reach to an elevation of nearly 3500 ft (Capt King Barom. Measurements.). On the East side of the ridge I saw for the last time Sandstone of the carboniferous series; the greater part or whole of this information being confined to the slope. —

The rocks which I now proceed to mention all belong to distinct & much a more remote period. — On The foundation stones of the dividing ridge are Granites, & reddish Quartz Rock, or a very siliceous sandstone. P Besides this, I saw a small quarry of a white, or yellow crystalline Limestone, almost deserving the name of Marble. 3435 —

A similar kind of Limestone is found in great quantities at Wellington & Muskgee, & is

823 verso

shorten
Granite, coarsely crystalling
silicen similar if without mica, syenite, conculeous boulders
angular embedded fragments cones
hillock of quartz. —

passage cut Porphyry & Trachyte. p.13
dikes
Trappean rock. quartz & hornblende

Clay slate. clearing
sandstone & limestone
age & order. —

824

1836 New S. Wales 12

well known from the caverns containing fossil Bones. — Beyond these rocks, we have a coarse grained granite, porphyritic with large Cryst: of Quartz & Feldspar. Riding onwards, we then meet much hard clay slate, with an irregular shattered cleavage, siliceous rocks, Granites & a considerable quantity of compact Trappean rocks; the commonest variety has a dark green Felkdspathic base containing numerous grains of Quartz. 3430

A few miles before reaching the open downs of Bathurst, the road crosses a considerable quantity of a pale brown glassy clay-slate 3437. It is traversed by thick massive veins of white Quartz: is regularly laminated; the laminae dip at a very high angle to the East running N & S. — It is remarkable, that as Capt. King informs me, that the the country to the waters North of Lake George (about 100 miles to the South of this spot) which divides the water, is composed of mica slate, & that the laminae run to truly North & South that the people use the direction as a guide through the forest.

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1836 New S. Wales 13

This is another instance of what Humboldt calls Loxodromism,1 in the more [illeg] rocks. — Beyond the glassy clay-slate we have that kind of Granite composed solely of Feldspar & Quartz & again close to this a dark green Feldspathic greenstone containing large Cryst of Hornblende. 3438

The downs of Bathurst of are so covered up it is difficult to see the rocks. — I believe they are chiefly Granites. — Capt King informs me that a few miles to the South East such is the prevalent substance & that there are interspersed many hills of white Quartz. — On my return I followed the Lockyer line of road; amongst the Granites I also saw some of these white hillocks. — A little to the West of the dividing range, the Granite had degenerated into a harsh, brick red or whitish Porphyry with Cryst of Quartz & Feldspar. 3439 3430 The Porphyry is evidently nothing but Granite, where the crystall Granitic-crystalline structure has been partially prevented. I saw in some places Trappean rocks. — The last Granite

1 What Humboldt termed 'loxodromism', is the parallelism of geological structures over huge distances, especially down mountain chains like the Andes. Darwin discusses loxodromism at length in the 'Cleavage' essay (DAR 41.59-77). [Gordon Chancellor]

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1836 New S. Wales 14

I met with to the East, was a little beyond Cox's river: it abounded in Quartz: In Angular fragment-like pieces of blacker closer grained varieties were included in the common Granite.

Bathurst plains or downs have a remarkable appearance from being entirely destitute of trees, whilst the country generally in all other parts is clothed with an open wood. The cause appears to lie in a covering of soil & Gravel, which smoothes over the underlying crystalline rocks.

The surface however is undulating & far from level. — The height of the lowest part of valley the downs, in the central valley of the river Macquarie is by Mr Oxley 2232 ft. (at the flag-staff of Bathurst). I mention this Diluvium (for it has no connection with the Macquarie, which for part of the year is merely a chain of ponds) from say the apparent infrequency of these substances in this colony.
Great interior plain fine for pebbles. Valley of Nepean.

Between Bathurst & O'Connell plains, the upper downs abutted on the broard central valley in the form of a terrace. I return to the same agent, which I believed has left the Shingle at on each side of the R. Nepean.

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1836 New S. Wales 15

In the imperfect section, which I have attempted to describe from Port Jackson to Bathurst we see two very distinct formations. —

The older one contains many varieties of Granites, Porphyry, Trappean rocks. — Mica slate & glossy Clay Slate, which possess a Northerly cleavage; Siliceous rocks & Marble. (a) (a) — The prevalent rock however is Granite, & the whole formation is remarkable by the abundance of Quartz. —

In the more modern & horizontally stratified formations, we have sandstones, clay, Iron stone, shales, clay-slate, & coal; as in the former Granite was far preponderant so here is Sandstone. — This latter formation immediately overlies the former. — The line of division of the waters appears to be formed by the crystalline rocks & the space between them & the sea coast is occupied, by the sedimentary deposits. — There can be no doubt but that the sandstone, consisting of grains of pure Quartz, cemented by white aluminous powder or ferruginous matter, has owes these materials to decomposed Granite; the Feldspar has

827 verso

(a) I may mention, that I saw in Capt. King's possession a slat of Limestone, containing the most beautiful petrifaction of such delicate Corallines as Flustra & Cellaria; This rock probably points out a division into two series; for I do not suppose it can belong to the same class with the marble. —

828

1836 New S. Wales 16

afforded the white substance & Mica the Iron.

We see from the abundant Quartz, very numerous little pebbles enter into the composition of the approximate sandstone. On the hills of Granite, the vegetables must have flourished which now form the layers of coal & carbonaceous shale. — In this view there is one difficulty; the inland upper parts of the sandstone platform have a slightly greater elevation than, with the exception of some points than than the Granitic country; that is with the exception of a few points such as Jock's bridge &c &c. —

Has rock the land nearer the coast been upheaved with greater force than the more interior parts? Is not this connected with the remarkable proximity of the Watershed line to the sea-coast; a feature so conspicuous in the Geography of New S. Wales ?.

With respect to the age of either of these two formations I believe no data exist to form any opinion. — I understand fossil shells are found at the Hunter, it will be a point of no small interest some future day, to discover the age of the great carboniferous series of New S. Wales

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(a) Yet from this country the materials of the sandstone were originally washed down. to be consolidated beneath the sea. —

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1836 New. S. Wales 17

I have as yet taken no notice, of what appears to me the most interesting part of the Geology of this Colony; namely the structure of the valleys in the elevated sandstone platform. — These are of so remarkable an appearance, that they are pointed out to strangers as well worth visiting: The two most best known views are, the waterfall near the Weatherboard Hut & Govetts leap near Blackheath. — Of both these Mr Martens,1 (an artist now resident in Sydney, who formerly accompanied the Beagle) has made correct & very beautiful pictures. — In both cases, the Stranger follows an insignificant rill of water, flowing down a slight depression, till he suddenly & without any preparation arrives on the brink of an immense precipice. He sees beneath his feet, at a depth perhaps of 1500 ft: an ocean of forest land. This depressed bay or grand valley appears on all sides to be surrounded

1 Conrad Martens (1801-1878), Draughtsman of 2nd voyage of Beagle after the departure of Augustus Earle at Montevideo.

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1836 New. S. Wales 18

by bare cliffs of horizontally stratified sandstone. These cliffs are so absolutely precipitous, that a person standing on the edge & throwing a stone can see it strike the trees, 800 or 1000 ft below him. — The main valley sends in all directions arms or bays, which receive at the base of the vertical cliffs the small drainage of the platform. —

So comple extensively surrounded is this lower valley with the precipices, that it is said, in order to reach the base of the Waterfall at the Weatherboard, it is necessary to go round a distance of 16 miles. — I do not know whether this is accurate, but that the inhabitants should fabricate such a story, shows how long far the line of unbroken cliff must run. — The two views alluded to, although affording strong examples of a peculiar & splendid scenery, yet represent the general character of the structure of the valleys. —

The Geologist is immediately astonished at the enormous

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1836 New. S. Wales 19

amount of matter, which the corresponding horizontal stratification on each side of the grand valley seems to prove to have been removed: — On a closer examination he looks to the upper valleys & sees they bear no proportion to the great abysses below, which they join. — the water. which is conducted by them, is at most an insignificant rivulet or mere chain of pools. — Again it will be found, that the arms from the main valley generally end in rounded & symmetrical creeks with vertical cliffs, & that the streams, which pour their water over the brink, will frequently enter on one side (a), but have there hardly affected the line of curvature; on the remaining sides of the little bays, as they may be called, the vegetation & form of land show, that running water have performed no great work. — This last conclusion, will I think be extended by anyone, who inspects the country, to its general structure.

In corroboration of this. I may add, that the Sandstone platforms. sends off spurs or

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(a) [sketch]
river

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1836 New S. Wales 20

promontories & leave Islands of the same configuration, in the low country. Indeed part of the amphitheatre, in this view at of the Weatherboard, is thus formed, as may be see in Major Mitchells excellent map, where Jamisons Valleys. joins Cox's River. — More than one person in the country, no ways interested with Geology, has remarked to me, that they never could behold these views, without imagining the sea had formerly occupied these basins or valleys. I certainly believe no other power could have modelled the land into its present form. —

But the question remains, could ever the tides or currents have removed such vast masses: — I think the answer would be doubtful. — If the agency of Debacles be attempted to be brought into play; it must be remembered, that the accumulations, called Diluvium, is in this country very infrequent & that on the Sandstone platform itself, not a

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1836 New. S. Wales 21

single pebble or boulder will be found, excepting the small ones of quartz out washed out of the underlying stone.

There is an additional & more strange peculiarity in the structure of the some of the valleys. I was taken to see, the head of the valley of Wolgan, where a steep & narrow cattle track has been cut down into the lower p valley.

When this path is once closed, the cattle are perfectly secure, as no other part of the surrounding cliffs is by any method accessible. The bottom of the valley is many hundred ft deep, but not quite equal of at the Weatherboard; its width is about 1/2 a mile, but very irregular. — The valley about 8 miles lower down contracts into a mere chasm with vertical sides; this is so choked up by fallen fragments & the course of the stream, that it is not only impassable by cattle, but

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1836 New. S. Wales 22

[writing in margin illegible]

that two attempts made by the Surveyors have failed. — It is said, a similar structure is found at Capertee, & I believe in some other places. The Goose.

Now in these cases it is impossible to believe that so many superficial square miles of stone. of the thickness of at least 1000 ft. has been removed by any force, which has been able only to excavate a mere crevice.

It is the same, whether we suppose this force, running water, the action of the tides, or an overpowering debacle. —

We must rather therefore conclude, that the strata never did extend across these spacious basins & valleys. — At first I thought, that in the general uplifting the force had failed beneath certain parts: this idea is inadmissible, from several reasons; especially, because analogy drawn from the structure of other mountains would induce one to believe certain parts then thus raised would then have been tilted or unequally lifted. —

I strongly suspect, that the sandstone

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835

platform was originally accumulated, so beneath a part of the sea, where strong currents brought together its materials.

Might we not then expect an irregular form, deep hollows & steep sides? this idea appears to agree with my conjecture about the escarpement of the Blue Mountains, & with the very frequent inclined pseudo-stratification. When the series of upheavals had commenced, the sea, occupying all the deep spots, would by its gradual action destroy the form of the banks & leave, as is so often the case seen, precipitous cliffs. (a)

In some of the cases, as for instance at the Weatherboard, where the valley does not contract, but expands into a wide & lower country, I do not doubt, the waves of the sea, by their unceasing labor, have produced a great effect. — Moreover, much loose sand, which the tides might have failed in removing from the bottom of these bays & creeks, at would, when the land had become dry, be removed to a great

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(a). Note

If it is believed that Sandstones are not consolidated, untill elevated & the water drained from them, the sea in the earlier stages of elevation will have had great facilities in deepening channels & in the formation of the coast cliffs. —

First impression

considering irregularity & formations

erosion

driven to subsidence but must be given up

not fresh water

inhabintant remark sea like Bays on present coast

But how can we suppose the sea can have excavated & what could determine it to excavate a great space in most of the platform

P The only light I can throw on this enigma is by remarking on [illeg] Sec & [Balaena]

already remarked on steepness of [illeg] banks if we suppose Sea can excavate shore of land bays by leaving to [illeg] of present sea

Coal

835a

[see separate catalogue entry]

Sturt Vol. I. xxxix. Intro1

Shoal Haven Gully 1200ft. about 1/4 of mile broad; country on each side level.-

Dry season return periodically after every

1 Sturtt 1833, 1:xxxix:

"At Goulburn Plains, however, a vein of limestone occurs, which is evidently connected with that forming the ShoalHaven Gully, which is perhaps the most remarkable geological feature in the colony of New South Wales. It is a deep chasm of about a quarter of a mile in breadth, and 1200 feet in depth. The country on either side is perfectly level, so much so that the traveller approaches almost to its very brink before he is aware of his being near so singular an abyss. A small rivulet flows through the Gully, and discharges itself into the sea at ShoalHaven; but this river is hardly perceptible, from the summit of the cliffs forming the sides of the Gully, which are of the boldest and most precipitous character. The ground on the summit is full of caves of great depth, but there has been a difficulty in examining them, in consequence of the violent wind that rushes up them, and extinguishes every torch."

See further notes in the Red Notebook.

836

1836 New. S. Wales 24

extent, even by the feeble drainage power of Australia. — It appears probable under another climate & with a longer lapse of time, one remarkable character of the valleys, the precipitous intersection of their courses, would gradually disappear. — I have been tempted to offer these imperfect notices & conjectures, in hopes that some one of the Residents, of whom many are so fully capable, will before long describe & explain the structure of the land & valleys of their colony. —

The general horizontal stratification & the absence give of Diluvium, give to this subject, at all times worthy of investigation, a particular interest. —

836 verso

My description of neighbourhood of Sydney agrees closely with Peron1 - The curious clayey substance has been described Phil Transact under name of Sydenyte.

All islands between Austra and Tasmania granitic Peron thinks Van Diemen's land long separ

From Sturts account not a pebble to be seen on Great Western Plain

1 Péron 1807. Text


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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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