214 



melaphyr the fragments of that rock are large and anguhir ; 

 but the congloiuerate as a whole is composed chiefly of felsite 

 and granite, and cannot be classed as a tuff. The dij) is as 

 usual about S. 70°. Irregular veinlets of iron oxide are seen 

 in both the sandstone and the melaphyr ; and cannot be 

 regarded as evidence that the melaphyr is intrusive. The 

 northern border of the melaphyr, as drawn on the maj), is 

 shown by these recent observations to be too far to the north at 

 this point ; and it is possible that a small transverse flexure or 

 fault separates this contact ledge from the remaining outcroj)s 

 of melaphyr in the next field to the west. In this field it is 

 quite noticeable that the melaphyr is more compact toward the 

 granite on the south or the supposed base of the flow, and 

 more amygdaloidal and scoriaccous toward the sedimentary 

 rocks on the north or the supposed top of the flow. Going 

 north from these ledges into the adjoining field we find, after 

 an interval of nearly 75 feet, or 15 feet beyond the fence, ()0 

 feet of fine conglomerate and sandstone with an a[)[)arent di[) 

 S. 45° ; 50 feet concealed ; and 10 feet of sandstone. These 

 exposures, which are marked on the map, must evidently be 

 referred to the same bed (3) which we have elsewhere found in 

 contact with the melaphyr ; and more recently I have discovered 

 north of these, email and obscure exposures of pur[)lc slate 

 (4), dipping S. 70°; and conglomerate (5). These scanty 

 outcrops serve to show that the Village series of strata probably 

 extends without essential change this far to the west. 



We come now to the interesting group of conglomerate 

 ledges in the field south of the melaphyr and Hockley Lane, 

 and l)ordered on the east and south by granite (see the map). 

 The relations of the granite and conglomerate are very inti- 

 mate, and could be fully known only by removing all the 

 superficial detritus from this area. Along the south side of the 

 field, especially, and on both sides of the fence, we pass 

 repeatedly and abruptly from the one rock to the other ; and 

 there are probably several or many bosses or knobs of granite 



