238 



between the conglomcriite ridges ; and this peculiarity is the 

 only fact that can be cited in support of the bed of slate 

 shown on the map south of this sandstone bed. That is, the 

 topography is suggestive of slate, but no outcrops have been 

 observed. Following this blank, conies a belt of fine con- 

 glonierate a good hundred feet in breadth. It outcrops boldly 

 on the southwest border of the garden, northwest of the 

 larger pond ; and can be satisfactorily traced westward along 

 the east side of Grove Avenue to a point 750 feet northwest 

 of Crescent Avenue, where it passes beneath the Pleasant Tlill 

 drumlin. The outcrops of this bed, in connection with the 

 preceding, first fully outline the great curve in the strike ; and 

 it will be noticed that while the lower part of this geii('r:il 

 section is based upon outcrops conforming with the eastern area 

 of the curve and dipping south, the numerous outcrops of the 

 upper half, yet to be described, follow the northern area and 

 dij) west. Northwest of tlie pond. Grove Avenue utilizes one 

 of the narrow slate lanes, and the slate, which is brown and 

 dips west aljout 30°, comes to the surface in the northwestern 

 extension of the avenue. The breadth of this slate is scarcely 

 30 feet ; and then follow in continuous outci'ops 30 feet in 

 breadth of gray sandstone, 40 feet of fine conglomerate, 30 

 feet of brownish slate, 90 feet of conglomerate with 

 streaks of sandstone, and 40 feet of gray sandstone. These 

 beds are clearly traceable along the strike for nearly one third 

 of a mile, as shown on the map: and the dip, throughout, 

 varies I)ut little from 30°, although constantly changing in 

 direction. 



We have now reached a slate valley of unusual breadth. 

 At the southeast end, near Grove Avenue, there is an obscure 

 outcrop of brown slate ; and greenish gray slate, changing west 

 to brown or reddish, is well developed on the west side of the 

 artificial pond. But the only complete section is in the 

 northern part of the valley. Here the outcrops, across the 

 strike, are almost continuous, and the breadth of the slate, 



