202 



purplish-brown slate banded with gray. Toward the north the 

 strike of these rocks changes to north-north-east, while in the 

 opposite direction it appears to curve gradually around to north- 

 west, and at last, near the road, to west-north-west, or even to 

 east-west ; the dip being in succession, west, south-west, and 

 south. Beyond the slate, in a westerly direction from Downer 

 Landing, the fine pebble conglomerate appears again, with the 

 same dips, a fault with the downthrow on the east probably 

 separating it from the slate. This conglomerate, like the first, 

 becomes grit and sandstone on the -west. It has a breadth of 

 one to two hundred feet ; and is succeeded, after a narrow belt 

 of brownish slate (partly concealed) , by a grayish and greenish 

 banded slate which is considerably contorted and has a westerly 

 dip of 40°-60°. This holds for perhaps five hundred feet ; and 

 then, after becoming in part of a purplish-brown color, it 

 passes without change of dip through sandstone and grit to small 

 pebble conglomerate ; and a few rods farther this is met by the 

 eastern border of the large triangular area of amygdaloid. 



To recapitulate ; the observed succession of beds charac- 

 terized by a westerly dip, from the drift-hill on the east to the 

 amygdaloid on the west, is as follows : — 



(a.) Conglomerate, becoming smaller-pebbled upwards. 



(5.) Sandstone. 



(c.) Purplish-brown slate, cut-off by a fault. 



(«.) Conglomerate, small-pebbled, changing to 



(6.) Sandstone. 



(c. ) Purplish-brown slate, upper part concealed. 



(e?.) Grayish and greenish banded slate. 



(c.) Purplish-brown slate. 



(6.) Sandstone, passing gradually into small-pebbled 



( a . ) Conglomerate . 



The best explanation of this succession seems to be that sug- 

 gested by the letters ; viz., a closed synclinal fold, with its axial- 

 plane dipping to the west, and having the strata repeated on the 

 east side by a strike fault. (See PI. 4, fig. 1. ) According to this 

 view, the gray slate (<i. ) is folded sharply upon itself in the cen'tre 



