Bd. CONTRIBUTIONS TO THE GEOLOGY OF THE FALKLAND ISLANDS. 7 
north as well as to the south by resistant quartzite ridges, the harbour itself being 
eroded in soft clay-slate and sandstone beds, the entrance forming a narrow trans- 
verse valley cut through the northern quartzite range. 
/■ \ 
Darwin has described and figured several detailed sections of these quartzite 
ridges. To his account I will add only a sketch of the quartzite hill N. of the 
valley in which the large Darwin-stoneriver is situated. To judge from Darwin’s 
description his figure 2 (p. 271) refers to the same hill, and it appears from a 
comparison between the two figures that my conception of the dip of the strata is 
different from his explanation. 
As to the relation of the quartzite to the clay-slate and sandstone of the low 
land Darwin wrote: 
»I nowhere actually saw the superposition of the clay-slate on the quartz, but 
in several places on the sea-shore I traced the most gradual transitions between these 
two widely different formations. It was particularly curious to observe how insen- 
sibly the gently inclined planes of stratification in the quartz disapperared, and the 
highly inclined cleavage-laminæ of the clay-slate, e.xtending in their usual course, 
appeared: it was impossible to point out where the stratification ended and the 
cleavage commenced. From the manner in which the clay-slate and sandstone often 
come up on each side to the base of the quartz ranges, I have no doubt that this 
rock is a lower and more arenaceous formation metamorphosed.» ' 
The tectonic features of West Falkland are still almost unknown. In the south 
— the only part of the island visited by me — I found no signs of real folding, but 
a gentle dip to the north between Port Stephens and Carew Harbour, and round 
Fox Bay the strata dip gradually SSW. 
To judge from the Admiralty Chart a mountain range runs in a SSW. — NNE. 
direction along the east coast of W. Falkland all the way from Fox Bay to the 
northern entrance of Falkland Sound. In the event of this being a folding ridge — 
which seems to me rather doubtful — it runs strait across the WNW. folding line 
of the western part of E. Falkland. Moreover it ought to be noted that there is 
^ Quart. Journal. Geol. Soc. 1846. P. 269 — 270. 
