175 
also points out that the ejected blocks of solid lava are wholly 
different in origin, and readily distinguished from the so-called 
voleanie bombs. 
The red slate referred to on page 55 as outcropping on the 
edge of the marsh, west of the Rockland House, is probably not 
a tuff; but it appears better to regard itas a slaty layer in the 
conglomerate. A similar layer occurs in the conglomerate 
south of Willow Ledge Pond; and, without wishing to suggest 
the exact correlation of these very limited deposits of finer sedi- 
ment, it has appeared best, on the map, to indicate the con- 
glomerate in the vieinity of the pond as extending westward far 
enough to embrace the second outerop of slate. 
There appears now little reason to doubt that the large out- 
crop of hard, slaty roek on the railroad, west of the Rockland 
House, is a true tuff; and it should probably, in spite of its 
finer texture, be correlated with the main bed of tuff at the base 
of Atlantie Hill. 
In the description, on page 67, of the faults crossing Cres- 
cent Hill, it should have been noted in connection with the third 
fault, which accompanies the small dike, that the dike itself 
marks a fault plane of later date than the other and compensating 
with reference to it. The two faults hade in opposite directions, 
and the only displacement of the strata actually observable is 
the elevation of the triangular mass of melaphyr between the 
two faults. It now appears probable, also, that there is one 
more fault on the southern slope of Crescent Hill than has been 
described in the text; and it has been so represented on the map. 
There appears now no sufficient reason to extend the fault 
which is supposed to cross the western end of Conglomerate 
Plateau southward to the granite and the boundary fault, as 
suggested on page 74; and it has not been so drawn. 
The position of the conglomerate overlying the melaphyr 
south of Conglomerate Plateau and east of Round Hill appears 
to be slightly synclinal, probably rising both to the east and west. 
It now appears improbable that all of the contacts of conglom- 
