[118]

538 skate                            Geology of southern part of T. d. F.–

The great feature – Slate formation.– extension – general characters: cleavage. [sketch and doodles with geological hammers] s universal:– dip general & strata in mountain features in the country (perhaps east west extremity dip more southerly). Proceeding to the W.– grand granitic chain.– Mica slate same dip.– channel & main chain quite parallel to the cleavage. on the outside coast numberless island, which would appear to composed of crystalline rocks & mostly allied to greenstone.–

More minute description S. S Bay: within Beagle Channell: Navarin & small islands: the alternation within Beagle channell.– Alternations of felspathic Wollaston island with slate (Cap FitzRoy). [sketch?] occurrence of amphibolic rock & subsequent movement to the SSW, but probably not very remote.– Extension & situation of Slate W of Ponsonby Sound: When describing the N part.– description of the granitic chain may be introduced: must suppose a slight turn & extension (perhaps as the slate hills occur to the NE of Admiralty Sound, it is as it ought to be.–

To return to the slate.

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Hardy Peninsula (felspathic rock).– Trappean rocks

2 Southern Trap Islands. More perfectly match conical form

1 Wollaston Island slate greywacke & common greenstone.

–Dissentation (granitic chain shows probability of ILLEG & upheaval being the same) of cleavage upheaving: & fissures: perhaps latter no more remarkable than columnar structure: (quadrangular) relation of ancient & greywacke's cleavage inexplicable:

Glaneros  Grand alluvial formation perhaps soon obstructed

Guanaco:– Mice Foxes

perhaps many boulders owe their origin to this – earth removed

Glaciers hollow (Alluvium remains only when protected from southern oceans

(occurrence of pebbles / on hill & fragments of greenstone)

Formation of Beagle channell triangular: original state: must have been of great depth from constant accession of pebbles: (did clearing out this produce the alluvium): no force of waves they are so soon broken: no signs of particular violence: it is nearly in same line as S termination of the east extremity

Only particular violence in Ponsonby Sound: Glaciers may be here described the Alluvium [sketch] Hill of boulders (Tierra del Fuego)

'2', 'More perfectly…form', 'quadrangular', '(occurrence of pebbles…of greenstone)'] pencil.

[119]

(3)    From data V P 4 drawn from the geolog of Tierra del.– the only imperfe conclusion I can come to (imperfect & strange) as it may be.– is that when the general WNW & ESE direction of cleavage took place; the inclination was generally to the SSW, but not universal: that perhaps distinct causes may have slightly altered it in plan: that with the direction of cleavage great mineralogical changes (as on a smaller scale (have endeavored to show in slate at Wollaston) have taken place.– & that the formation of mountain ridges is to be attributed to the line of harder rocks withstanding the destroying agents: the slow It has is hugely probable my data may be wrong & imperfect, but this is only conclusion I can come to.– a> This leaves out the considerationof the white horizontal bands.– The strongest argument against the mountains, being ridges, which have are harder in these hill being a continuation of great [illeg]  chain of the Andes:–

a> I grant it be a monstrous supposition to imagine such enormous wearing away, I only give it to show this tendency of the facts adduced (not doubting the [illeg] of my data)

It appears to me an accurate study of direction & dip of cleavage – as connection with the elevation of mountains will alone explain its real nature & whether any change has taken place of common cause [illeg] not parallel to [illeg] of elevation:

'V P 4', '& whether any change…of elevation:'] pencil.

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(4)    Fissures are parallel smooth planes at considerable [illeg] apart cutting the rocks generally at high angle.– these are more than one set present at the same time.– their nature perhaps is at analogous to columnar structure.– The following taken from Navarin Island: (& when in trappean rock fragment this pressure is alone [illeg])

It is to be remarked that the out of 5 cases, there are two pairs the same: which is curious & gave grounds to conjecture there is some regular law:–

We have shown the identity suppose of elevation & cleavage & is excessive improbability if cleavage originally any position but [intermediate] we must think either mountains are not elevated or cleavage originally lower – We here take improbability of this – hence monstrous supposition Being in it remains to consider [illeg] masses. Andes

'(& when in trappean…pressure is alone [illeg])', 'It is to be remarked…masses. Andes'] pencil.