156 THE VICTORIAN NATURALIST. 



Katherine, and forming, like the granite, low broken ranges and 

 hills. The name was bestowed upon this formation first by 

 Leichhardt, though now almost obsolete in geology. The country 

 formed by this rock is even poorer than that of the granite, the 

 soil being a grey pipeclay of the most worthless description. 



Crystalline Schists, Slates, &c. — These form isolated 

 patches of low, stony ranges, not exceeding 500 feet in height. 

 The strata form a series of anticlinal folds, abounding with 

 quartz reefs and mineral veins of gold, silver, tin, copper, lead, 

 antimony, and other metals. I believe that these strata, which 

 we may term archsean, have been folded into the ridges by the 

 intrusion of the granite when the great system of the paleozoic 

 rocks was broken up into fragments and crushed into folds. 

 Possibly, at this time, some of the veins may have been injected. 

 In the centre of the ranges, generally speaking, the gold is 

 found ; while the tin, lead, silver, and copper seem more restricted 

 to the edge of the schistose formation, or on the very boundaries 

 between that and the granite. The archsean rocks are generally 

 conspicuous for the large amount of mica they contain. Where 

 metamorphic action has been very complete the rock is altered 

 into a white quartz, with a mass of large crystals of mica (Musco- 

 vite) three or four inches across, mingled with rich oxides of 

 metals, especially tin. Otherwise the crystalline schists are highly 

 variegated, and glistening with small particles of mica. They are 

 much faulted with systems of joints which do not correspond 

 usually with the planes of stratification. The slates are highly 

 fissile, with lenticular masses peculiarly elongated by pressure, the 

 longer axis being parallel to the plane of lamination. 



Limestones. — Resting upon the southern edge of the crystalline 

 schists is a small patch of limestone strata of not more than a few 

 acres in extent. The strata are broken by denudation into the 

 most fantastic figures and pinnacles. Some of the strata seem to 

 have been much softer than others, leaving heaps and piles of 

 overlapping layers, sometimes of hard, flaggy stones and blue 

 limestone. The heaps of such fragments, little more than a foot 

 in diameter, make the locality appear like a tiler's or a potter's 

 yard. Strange to say that the area, small as it is, has in its centre 

 one of the very rich silver, lead, and copper mines of Arnhem's 

 Land. 



The limestone is completely marmorized and destitute of fossils. 

 It is, however, easy to see that it belongs to a very ancient system, 

 not later than the paleozoic. There is, however, another Hme- 

 stone outcrop on the edge of the desert sandstone, and forming 

 a broken stony country like the desert sandstone itself, on the 

 sides of the valley of the Katherine River, near the telegraph 

 station, about 200 miles south of Palmerston. This limestone 

 has an old look, being completely marmorized, though there 



