NORTHWEST SHORE OF LAKE SDPERIO R. 373 



darker-coloured, of a finer and more compact texture, and bearing no little resem- 

 blance to the metamorphosed sandstone of Black River. These beds contain nodules 

 of chalcedony and agate. 



On the tops of the highest ridges of this range, and overlying the great green- 

 stone ridges, is a rock in all respects like the amygdaloid, except that it contains 

 no amygdules ; and the peculiar green mineral (thalite) , so abundant in the cells of 

 the amygdaloid, appears to be disseminated through it in small particles, giving to 

 the rock an aspect of homogeneousness, and a very peculiar, rough, irregular frac- 

 ture. It is red, coarse-grained, and, upon exposure, weathers with a grayish- 

 coloured, nodular fracture. It is distinctly bedded, and conforms to the dip of the 

 amygdaloid, which is east-southeast and southeast, from 18° to 19°. 



In proceeding down the lake-shore from Two Island River to the Inaonani River, 

 the rocks are exposed in detail for nearly the whole distance, consisting of beds of 

 trap, volcanic grits, and metamorphosed sandstone. About two hundred yards 

 above the mouth of Inaonani River, the following section occurs : 



1. Basaltic rock. 



2. Volcanic grit; amygdaloidal. 



3. Brecciated conglomerate; the fragments 



being amygdaloidal. and the cement a 

 ferruginous clay, with thin clay seams. 



4. Same as 3, with a clay seam intervening. 



5. Volcanic grit ; very amygdaloidal ; in 



irregularly bedded layers. 

 0. Volcanic grit: more compact; fewer amyg- 

 dules; and regularly bedded. 



About seventy-five yards above this place is a fine exposure of corrugated or 

 wrinkled strata. The wrinkled beds are about two feet thick, the upper part show- 

 ing the corrugations most, although they pervade the whole rock. The position 

 this rock seems to occupy here, is between the layers of volcanic grit at the bottom 

 of the preceding section, and a still lower bed of the same rock. These rocks are 

 all traversed by veins of ferruginous clay, from half an inch to eight inches wide, 

 and carrying calcite, zeolites, and occasional traces of copper ore. 



A little further up the Lake the section exhibits the following members : 



1. Basaltic bed. 



2. Volcanic grit ; no amygdules. 



3. Volcanic grit ; amygdaloidal. 



4. Shaly amygdaloid. 



5. Volcanic grit. 

 G. Volcanic grit. 



These rocks dip southeast into the Lake, and each bed seems to have been depo- 

 sited on a very irregular surface. 



Beyond this point, and in the direction of Two Island River, the following Section 

 occurs, in ascending order :* 



* See Section from Inaonani River towards Two Island River, PI. 1 N, Sect, 4. 



