OF THE ROCKS OF LAKE SUPERIOR. 255 



No. 593, or to the Palisade beds. The specimen is precisely like the specimens 

 taken from the arch at the Great Palisade. Weathered surface, polished. 



GOO. Bears N. 45° E. Basaltiform trap. Colour, grayish black. Very fine 

 granular; homogeneous; compact. Joints with carbonate of lime in thin seams. 

 Weathered joints, with a thin, dirty yellowish coating. Weathers like the Basalt 

 of Aussig, in Bohemia. This rock differs entirely in structure and appearance from 

 the N. 45° E. dikes of greenstone, of which No. 589 is a specimen. It resembles 

 more nearly some of the N. and S. dikes. It probably belongs to an older period, 

 as it is traversed by a N. 30° E. dike a short distance below Passabika River. 

 The fracture of this rock is disposed to be conchoidal, and its weathered surface is 

 smooth. 



601. Basalt— bears N. 30° E. Narrow; traverses No. GOO in the middle of the 

 second bay below Passabika River. Resembles this last rock so much that it would 

 be difficult to distinguish them in hand specimens. The joints appear to contain 

 epidote. Weathered surface, smooth, black, and somewhat greasy to the feel. 



602. Metamorphosed rock — has a syenitic look, and is composed of deep flesh- 

 coloured felspar and magnetic iron, Avith, probably, some hornblende, though this 

 last mineral is not very obvious. It affects the magnet powerfully. The iron is in 

 grains and segregations. These beds are associated with No. 595 ; and are, no 

 doubt, the same as No. 593. It presents a semi-crystalline appearance ; has a rough, 

 irregular fracture ; and the colour is that of the red felspar, which predominates 

 over the other constituents ; the large grains of magnetic iron give it, however, a 

 mottled appearance. It weathers with a smooth, irregular surface, the irregularity 

 being caused by the iron disintegrating more easily than the felspar. 



603. Bears N. 30° E. This is a dolerite — and compares exactly with a specimen 

 of dolerite, from Sternheim, near Hanau, in Germany. Colour, dark bluish gray, 

 with a greenish tint. Fine granular ; homogeneous ; joints, rusty ; magnetic. On 

 the weathered surface, numerous grains of magnetic oxide of iron may be detected. 

 Fracture, somewhat irregular and rough. This dike, which is a wide one, is believed 

 to traverse a N. 5° E. one. It disintegrates easily ; and the metamorphosed rocks 

 traversed by it have their joints and cavities filled with zeolites. It crosses Riviere 

 des Franchises, near its mouth, and at its junction with the metamorphosed rocks 

 in the bed of that stream ; contains nests and druses of copper ore, and some native 

 copper. The greenish tinge is due, probably, to the dissemination through it of 

 epidote, in minute particles. As the mouth of Riviere des Francaises is approached, 

 the trap becomes amygdaloidal. This occurs near its junction with the sedimentary 

 rocks. 



604. Breccia — at the junction of No. 603, with the sedimentary rocks. The 

 fragments derived mostly from the shaly beds. Very cavernous ; the cavities being 

 filled with zeolites, principally laumonite. Some carbonate of lime and copper ore. 

 Fragments exceedingly rough, irregular, and jagged. 



605. This is a metamorphosed shale ; but bears some resemblance to some of the 

 N. 5° E. narrow trap dikes. It is enclosed in No. 603, in both large and small 

 fragments. No dike is to be seen of this character at this place, and as it resembles 

 the metamorphosed shales on the Lake shore, near the mouth of the Brule, I class 



