24 The American Geologist. •^"'^■' i^*^*- 
morphic material placed under it being reidilv referable to one 
or the other of the two great divisions. Indeed, the mapping of 
the region on a three-fold basis brings out some incongruities; 
as in the eastern part of the field mapped by Bailey ('98, map), 
where a large patch of the Golden ville is shown adjacent to 
Halifax strata, with none of the "banded argillyte division" be- 
tween . 
On the whole, therefore, it seems best not to name a third 
formation until stronger proof has been presented of its im- 
portance as a separate stratigraphic part of the Meguma series. 
Erosion from top of scries. — The original summit of the 
series has been lost through erosion, or at least has never been 
found in the most favorable places — the centers of svnclines. 
Thus we have no knowledge of the thickness of the undenuded 
Halifax formation. Moreover, we have no adequate criterion 
by which to judge how much of it has been lost. The small 
amount of territory- covered by it at present, scarcely five per 
cent, of the area of the series, indicates that a large propor- 
tion of its original hight must have gone. 
At the west end of Tor bay, near the eastern extremity of 
the province, there are two very strong synclines of adalusite 
schist. Faribault ('87, p. 149) regards these as perhaps a 
superjacent series. But they appear to be better regarded as 
a more highly metamorphosed part of the ^leguma ; for if they 
are a newer series conformable with the lower, the Halifax 
formation which immediately underlies it is, complete, only 
1800 feet thick. The mining settlement of Rawdon is situated 
on reddish slates which are thought by some to be a formation 
overlying the Halifax conformably ; but as to that there is no 
conclusive evidence as yet. 
Thickness. — Estimates of thickness vary greatly. Hind 
(70, 70% 70^) called it 3,000 feet. Bailey ("98, p. 46) gives 
3,000 feet as a probable minimum for the black slates. But 
this estimate does not include the "banded argillvte division," 
at least a part of which probably can be regarded for the pres- 
ent as within the Halifax. If it really represents a westward 
thickening of the thin bands of the east, it is fair tentatively tO' 
include all of it within that formation. No statement is made, 
in the paper referred to, as to the thickness of these banded 
