[118]

538 shake

Geology of southern part of T. d. F. ─

The great feature ─ Slate formation. ─ extension ─ general characters: cleavage. [4 small sketches or doodles] s universal:─ dip general & strata in mountain features is in country(perhaps West extremity dip more Southerly). Rounding 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 the composed of crystalline rocks & mostly allied to greenstone.─

More minute exception S. S Bay: within Beagle Channel. Navarin & small islands: the alternation within Beagle channell. Alternations of Felspathic Wollaston island with slate (Cap Fitzroy) 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 hold occur to the NE of Admiralty sound, it is as it ought to be.─

To return to the slate.

[118v]

Haig Peninsula (Felspathic rock) Trappean rocks

2 Southern Trap Islands. More perfectly match conical form

1 Wollaston Island slate greywackes & common greenstone

─Dissentation granitic chain shows probability of laws & upheaval being same of cleavage upheaving: & fissures:

—perhaps latter no more remarkable than cleavage structure: relation of ancient & greywacke's cleavage inexplicable:

Chonos

Grand alluvial formation perhaps soon obstructed Guanaco:— Mice Foxes perhaps many boulders over these origin to them ─ earth removed

Glaciers hollow (Alluvium remains only when protected from Southern oceans;occurrence of pebbles / on hill & fragments of greenstone

Formation of Beagle channel Triangular: original strata accession of pebbles (old cleavage out this produce the alluvium): no force of waves they are so soon broken: no signs of particularviolence: it is nearly in same line as S termination of in East extremity

Only particular violence in Ponsonby Sound: Glaciers possibly have been described the Alluvium

[sketch] (Tierra del Fuego)

[119]

From data V P H drawn from (3) 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 distinctly caused may have slightly alter it in plan: that with the direction of cleavage great mineralogical changes (as on a smaller scale (have endeavored to show in slate at [illeg] )have taken place.─ & that the formation of mountain ridges is to be attributed to the line of harden rocks withstanding the destroying agents: the slower It has is hugely probable my data may be wrong & imperfect, but this is only conclusion I a) can come to.─ This leaves out the [illeg] of the white horizontal bands.─ The strongest argument against the mountains, being ridges, which have are harden in their hill being a continuation of great running  chains of the Andes:─ a) I grant it be a monstrous supposition to imagine such erroneous wearing away, I only give it to show this tendency of the facts adduced not clearly on [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 be of Elevation.

[119v]

(4) Fissures are parallel smooth planes at considerate dates apart cutting the rocks generally at high angle.─ these are more than one act present at the same time.─ their nature perhaps is at analogous to columnar structure.─ The following taken from Navarin Island: (when in Trapp rocks fragment this pressureis alone movable)

It is to be remarked that the out of 5 cases, there are two pairs the same; which is curious & gave ground to conjecture there is some regular Law:─

We have shown the identity suppose of elevation cleavage & is excessive improbability if cleavage originally my position but [illeg] we must then 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] ridges Andes