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(1)

new form. sandstone (like (2576 rather harder) ferruginous acicular plates in concretionary structures also veins of cyst. carb of line; passes into a quite white & softer sandstone & thence again irregularly into white aluminous. —

x frequently rest on a hard greenish black sandstone, distinct grains of quartz cemented together (2581): there is much ferruginous breccia of the soft white pieces, exactly like at Chiloe. These & white alum beds generally superior. — There is also much very soft earthy stone with minute white imbedded mineral looking like porph earth. — color dark brown (2582) or red: — The covering of the cliff soft dry friable reddish earth — doubtless same as to; South. would not be supposed to be aqueous deposit but capped with shells. — V gel Blackened but to very short depth: —

Contains lignite & silicified wood in abundance. — Also very few shells; either impressions (2583 in micaceous brown sandstone) of Venus Solen &c & sev others vestiges converted into lime. — Shells too imperfect to recognize. — Form same as at Chiloe. — Rather coarser not so many concret: chiefly differs in lines of pebbles being numerous. — some part many lines — generally small, less than egg — Consist of clay-slates passing into porphyries, some red, generally blackish or green — with very few & minute crystals: [sketch] When a person approaches the older slate which forms point — meets great bed of

page in pencil

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to common horizontal concretion of tertiary strata

Elevation — Recent shells

B. Blanca. ornithology

352

2)

of peb coarse pebbles, angular & rounded — composed of the neighbouring slates & to the quartz veins. — Is seen on other side of Is^d to be thick conformable bed. — The form originally reposed on this old first slate —

These latter consist of black glossy clay slate, 3685 which is either smooth & over laminae, or appears abrased is [illeg] & laminae more contorted 2584 more abundant. — In spots immersed immense number of quartz veins. — cleavage here irreg. — There is some light brown stock of same construct 2586: — I imagine I see in these the construction of the ampelite = Cleavage at regular dip strike generally small: runs NW & SE: in the plain W & S.

These rocks are only found on P of Quinquina & the portions of which transverse at Pen: of Lamuy the softer strata to the South: This part is traversed by very many dykes: There is some shade of difference of the mineralogical nature of allum.

One may perhaps conjecture that they are of slightly different age although possessing nearly same direction & most within a yards of each of them: Beginning at the southern one — (they all lie within space of 1/4 of a mile)

(1) a very narrow dyke 4 or 5 inches wide composed of pale slate with feldspathic rock (2581) is vertical, thins out & thickens very suddenly. is seen terminated upwards by a round head. Vide Fig. 1. — (2) an irregular dyke, running NW & SE

of peb coarse pebbles...1/4 of a mile)] in pencil

352 verso

From 9— to 15 ft wide. nearly vertical. — traveling off sending off branches composed V. Fig.2. — composed of dark grey brilliant dolerite (2588) with glassy feldspar. — On the northern wall, the strata dip very regularly to NW as if tilted by this the slate here dips SW: & then have same strike with line of dyke: — (3) — About 18 inches wide composed of feldspathic rock blended with red particles very little smally crystalline (2589) followed for some distance the laminae strata of the calc: of slate & then suddenly bulging out, showed its true dyke-nature. — (4) a mass of narrow reticulated veins (evidently injected) composed of a strong mottled base with large layers of quartz & earthy feldspar (2590). — (5) dykes about 25 ft wide irregular chiefly composed of a very curious snow white stony feldspathic rock with large octagons of quartz (2592): part of the dyke was in a friable state of white friable powder. — Is not such material comes from volcano the origin of the white aluminous beds of Patagonia, Chiloe & here. — part of this dyke is constituted of same substance as the part a partially decomposed feldspathic greenstone base with large irregular crystals of feldspar & layers of quartz (2591). This dyke runs NW & SE, on its northern wall the slate dipped regularly to the NE by N, as if tilted by the dyke. — (6 & 7) dykes for 10 to 20 ft wide inclined composed and the last variety (2593 2591) & (8^th) nearly the same

The [word deleted] last was inclined & runs rather more E & W than NW & SE nearly W & E: all these last varieties strongly remind me of some of the dyke at north part of P. Tres Montes traversing the granite & mica slate. — I believe there to be more than these but had not time to examine them. —

353

3) other side

May be when that the extreme point of island has a bluff & [illeg] evidently formed by the upheaval of these slates:

But that the general direction is about NW & SE. & from this & similar position are clearly perhaps are influenced by cleavage of slate, although very often having broken through its restraint:

I have said nothing about the stratification of the tertiary formation. — At northern part the dip is at about ∠ 30° to SW by S — seen in ship — satisfaction of dyke right across Island — seen by single lines of pebbles in fine sediment: some little curvilinear.

Again ridge of thick slate plain — perhaps horizontal & South extreme is formed by N by W dip generally. That [3^d] one plain ? up to more than nearly 40° — The upheaved not quite regular dip varies — basset edge curved — Clearly owing to paps such an extreme. — Form of Island protected by mica slate owing to degradation

The fourth band of disturbance in S. America.

[sketch] ؟ Whether irregularity in direction of slate here & at Valdivia may be owing to these having been horizontal & so showing better the results of elevations & violence: the presumption is drawn for small regular dip seen near the some of the dykes

Tilting beneath the sea

All part of tilt at Concepcion: beds deposited on mica slate

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Elevation — sorts of shells — at least 400 ft

Trochus. full of carb. Concholepas — Balanus. fissurella. Mytilus. —

The fact that only the northern part of Island is composed of the mica slates seems probably owing to their elevations by this system of dykes — Their direction to a certain degree has been apparently influenced by the strike of the cleavage, although very often breaking through the constraint of the laminae. —

In At northern boundary part of Island the slates dip NE. At Near to the extreme southern dyke it would appear dips to opposite direction S to SW. — It would almost appear like an anticlinal line; the band where dykes are most numerous being the axis. — I do not feel certain, for the dip is so very variable as is seen in proximity with the quartz veins: but the fact is worthy of attention, for in no locality to the South could I find any sort of proof in the older slates of such upheaval. Here the tertiary strata will prove such to have taken place & of course it is probable in every locality. age of dyke diff. mineralogical structure — supposed nearly horizontal laminae of slate. —

necessary to represent elevation.

form of island protection —

Could not see any alteration in neighbouring slates

Elevation — sorts of shells — at least 400 ft] in pencil

form of island protection —] in pencil