352 



DESCEIPTION OF THE COUNTRY 



of greenstone, about eighty feet in thickness, and making a fall. It bears northeast 

 and southwest. 



Three hundred yards above the falls, the metamorphosed slates are overlaid by 

 a bed of volcanic grit (No. 359), very amygdaloidal, and containing small grains of 

 native copper. It is only seen in low ledges at the margin of the river, the bed of 

 which it continues to form for the distance of a mile, where it disappears under 

 clay and marl beds, from fifty to a hundred and fifty feet in thickness. These 

 deposits continue for another mile, when beds of metamorphosed sandstone (No. 

 361) come up, and show themselves for the distance of half a mile, dipping to the 

 southeast at an angle of 11°. The exposure here is about two hundred and fifty 

 feet thick. The rocks are again concealed by clay and marl beds for a mile and a 

 half, when No. 361 again appears, with alternations of compact and fissile shales. 

 Some of these shale-beds are highly metamorphosed, and assume a columnar 

 structure. These rocks continue for half a mile, when the river is crossed by a 

 dike of greenstone (No. 362), bearing northeast and southwest. The columnar 

 beds of shale are amygdaloid, the cells being filled, generally, with laumonite. 

 Before reaching the dike (No. 362), a quartz vein occurs, with native copper 

 disseminated through the veinstone (No. 367). 



Three hundred yards above the last-named dike, the river is crossed by another, 

 bearing northeast and southwest, over which there is a fall of eight or ten feet. 

 Between these last two dikes, the strata of metamorphosed sandstone and shales 

 (No. 363) are bent upwards, and form an arch about twenty-five feet in height. 

 The lower beds, which disintegrate easily, have been worn out by the action of the 

 river, and a cavern of some depth has been formed under the arched rocks, as 

 shown in the sketch below. On one side of the arch the dip is to the southeast ; 

 on the other, to the northwest. 



Beyond this point, for the distance of a mile, the river runs in the line of bearing 

 along the side of the dike, which is the only rock exposed, as far as exploration 

 was made. 



Among the debris of this river, I saw numerous fragments of veinstone contain- 



ARCH OF METAMORPHOSED SANDSTONE AND SHALE. 



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