Page:The Geologist, volume 5.djvu/69

Rh isolated masses of slate preserved their dip unaltered in the midst of granite which appeared to have a dip in the same direction. Passing north-westward towards Namaqualand, I saw the slate near Heer- lozement so little altered and so like some of the fossiliferous rocks of the Eastern Province that I much regretted that my engagements did not permit of a closer examination of it. At Olifant's river the rocks, Still with the same strike as in Cape Town, viz. nearly magnetic north (north 30° west), had assumed a micaceous and talcose character, and on the northern bank of the river were much impregnated with iron. Four or five miles beyond Kokonap I saw the slate for the last time till I met it at the Orange river, and here it abounded in a peculiar form of cyanite which I afterwards found in great abundance in the gneiss and mica-schist of De Kiet, near Hondeklip Bay. Some grassy country intervened between this spot and the next where rocks were visible. These were felspathic in great variety. I could not get a satisfactory observation of their dip for some days' journey, perhaps owing to the little experience I had then of rocks of this class. There are few things I have more to regret in the way of lost opportunities than the want of a careful examination in detail of the country within ten miles' radius of the lowermost ford of the Olifant's river. It would include a section from the clay-slate to the Upper Silurian of Bain which are found in the Cederberg as well as the passage of the former into the felspathic rocks of Namaqualand. Bain has no hesitation in affirming this change, and I have every reason to think that he is correct; but believing as I do in the identity of his clay-slate and the Upper Silurian, I cannot but regret that I was unable to make a thorough examination of the country. I believe Bain's separation of the clay-slate from the Upper Silurian (Devonian) are drawn here as elsewhere from the position of the quartzite crossing the slate and underlying the Devonian. Is not this evidence identical with that on which metamorphic formations are assigned to widely distant epochs in Europe?

In addition to the want of time and of experience referred to, I have to regret the loss of a note-book in which my observations on the rocks in the earlier as well as later part of my journey in Namaqualand were inserted. I cannot therefore tell from my own observations how the strike of the rocks which was north 30° west at Olifant's river, assumes a nearly east and west strike at Springbok Vontein. As we pass northwards it takes a more northerly direction, and at Oograbis it is north 60° west, and at Annies, on the Orange river, it resumes its north 30° west strike with its slaty character. I have no hesitation in affirming the passage of the slate into felspathic rock here.

Assuming, then, the metamorphosis of palæozoic rocks into gneiss, mica-schist, etc., I will merely reiterate my firm belief that those of Namaqualand are the changed condition of the great mass of slaty beds which extend from the mouth of the Fish river in the east to Cape Town, and thence to Olifant's river, and at various points contain fossils which have been referred to the Devonian epoch by geologists of Europe. I again admit that the evidence by which I