99 
indistiaguishable from that flow on the east side of the bay. 
It is never amygdaloidal, but often somewhat breeciated. The 
fault just referred to must, therefore, downthrow to the south- 
east, but probably not more than 20 or 30 feet, possibly less. 
Doth this displacement and the preceding one, parallel with it, 
are evidently added to the boundary fault, so that this now 
becomes sufficient to conceal entirely the basal conglomerate on 
the downthrow side. The first melaphyr is overlain in regular 
order by the second conglomerate (Fig. 12), which is thus, 
in consequence of the increased displacement, brought vis à vis 
with the strongly contrasting basal conglomerate (Fig. 13). 
The second eonglomerate contains so much melaphyr debris 
derived from the underlying flow that it is not always easily 
distinguished from the brecciated portions of the melaphyr. It 
is also the richest in red jasper of all the Rocky Neck strata, 
agreeing perfectly in this respect with the same bed in the 
porphyrite hills of Nantasket. This highly jaspery conglom- 
erate is well exposed on the shore for nearly two hundred feet, 
before it gives way to the underlying melaphyr, which extends 
150 feet farther, but bears several distinct outliers of the con- 
glomerate, as mapped. These outliers are seen to rest upon 
а very uneven surface of the melaphyr; but the normal dip 
is plainly S. E. 10° or more. At the northern edge of the 
nielaphyr it seems to end quite abruptly ; but the narrow beach 
between it and the puddingstone on the north is partly occupied 
by the firm, jaspery, second conglomerate,— another outlier 
let down by faulting. 
We have now reached the north end of the northeast-south- 
west fault which has already been seen to bound the first mela- 
phyr on the northwest. It appears to be a double fault at 
this end (Fig. 13) ; and following 1t southwest, we find that it 
encloses not only the depressed outlier of the conglomerate, 
but also an isolated ledge of the melaphyr with traces of the 
conglomerate upon it. 
The hill or ridge just described, composed of the first and 
