GEOLOGICAL FEATURES OF ST. CROIX RIVER 111 
SESSIONAL PAPER No. 38a 
seen from St. Andrews or Chamcook mountain, a conspicuous feature in the scenery 
of Passamaquoddy bay. 
On its southern side, Passamaquoddy bay is separated from the Bay of Fundy 
by the chain of the Western Isles, the largest of which is Deer island, while the 
smaller, including Adams island, Simpson’s island, Casco Bay island, Indian island, 
and many smaller islands, he along the southern side of the latter. In Deer island, 
and again in Campobello, a large island lying to the south and west of the latter, 
separated by the Eastern Passage, and opposite the town of Eastport, the rocks are 
much older than any found in this district. They consist largely of diorites and 
felsites, associated with chloritic and horn-blendic schists and are supposed to be of 
Pre-Cambrian age; but among the smaller islands, some are Silurian and others of 
Devonian age. The rocks of Eastport island are of Silurian age, consisting largely of 
rhyolites resting upon fossiliferous slates similar to those of the Mascareen shore. 
The west side of Passamaquoddy bay north of Eastport is made up of red sand- 
stones and conglomerates similar to those of the St. Andrews peninsula and of Upper 
Devonian age. They extend through the township of Perry, where they contain 
Devonian plants, and form the shore northward to within a few miles of Robbinston, 
where they meet and overlie the granites already referred to. 
This sketch would be incomplete without some reference to the geology of Grand 
Manan, for though this island is outside the limits of the area under discussion, it is 
a place frequently visited by the members of the Biological Station staff, the sur- 
rounding waters being one of the most interesting fields on the Atlantic seaboard for 
marine scientific research. The island lies at the mouth of the Bay of Fundy, and 
about twelve miles distant from the eastern shore of Campobello. It is about fifteen 
miles in length, while its breadth varies from two to seven miles. Both physio- 
graphically and geologically it embraces two tracts of which the one, the eastern, is 
low and bordered by numerous islands, while the other or western, is considerably 
higher, without islands, and fronting the waters of the bay in an almost unbroken 
line of precipitous bluffs from 300 to 400 feet in height. The rocks of the eastern 
shore, and of the adjacent islands, where are all the settlements, consist of a series of 
slates and schists, with some conglomerates, which are believed to be mainly of Pre- 
Cambrian age, though obscure fossils are said to have been found at one point, near 
the Swallow-tail light. 
The greater portion of the island, however, including all the uplands, and the 
western shore, which are uninhabited, is made up of rocks of much more recent origin, 
these being a series of trappean rocks, dolerites, basalts, and amygdaloids, of Triassic 
age, and similar to those which constitute cape Blomidon and the range of the North 
mountains and Digby Neck, in Nova Scotia. At some points when the tide is low, 
they may, as in Nova Scotia, be seen to overlie red sandstones, which are also of 
Triassic age. The relations of the traps to the older rocks of the islands may be 
well seen at either the Northern or Southern Head. At both of these points and 
again at Dark Harbour, midway of the length of the island, the columnar traps con- 
stitute some very bold and picturesque scenery. 
Not only do the Perry rocks form the western side of Passamaquoddy Bay, but 
also the whole of the St. Andrews peninsula. As seen about the Biological Station, 
and elsewhere, they are noticeable for their brownish red colour, for their coarseness, 
and for the fact that they are made up mainly of metamorphic rocks, derived directly 
from the underlying formations, including especially granite and rhyolite. In these 
respects and in their stratigraphical relations they are markedly similar to what, in 
other parts of New Brunswick, have been referred to the Lower Carboniferous period, 
and are so represented in the Geological Survey maps; but recent observations else- 
where have tended to confirm the opinion first advanced by the late Sir William 
Dawson, and based upon their plant remains, that they should more properly be 
