The Geological History of PlantsDawson, John William, Sir
Science
The Geological History of Plants
Dawson, John William, Sir
Paleobotany
In the Bay des Chaleurs, similar rocks exist with some local variations.
In the vicinity of Campbellton are calcareous and magnesian breccia
or agglomerate, hard shales, conglomerates and sandstones of Lower
Devonian age. The agglomerate and lower shales contain abundant remains
of fishes of the genera _Cephalaspis_, _Coccosteus_, _Ctenacanthus_,
and _Homacanthus_, and also fragments of _Pterygotus_. The shales
and sandstones abound in remains of _Psilophyton_, with which are
_Nematophyton_, _Arthrostigma_, and _Leptophleum_ of the same species
found in the Lower Devonian of Gaspé Bay. These beds near Campbellton dip
to the northward, and the Restigouche River here occupies a synclinal,
for on the opposite side, at Bordeaux Quarry, there are thick beds of
grey sandstone dipping to the southward, and containing large silicified
trunks of Prototaxites, in addition to _Psilophyton_. These beds are
all undoubtedly Lower Erian, but farther to the eastward, on the north
side of the river, there are newer and overlying strata. These are best
seen at Scaumenac Bay, opposite Dalhousie, between Cape Florissant
and Maguacha Point, where they consist of laminated and fine-grained
sandstone, with shales of grey colours, but holding some reddish beds
at top, and overlaid unconformably by a great thickness of Lower
Carboniferous red conglomerate and sandstone. In these beds numerous
fossil fishes have been found, among which Mr. Whiteaves recognises
species of _Pterichthys_, _Glyptolepis_, _Cheirolepis_, &c. With these
are found somewhat plentifully four species of fossil ferns, all of Upper
Erian types, of which one is peculiar to this locality; but the others
are found in the Upper Erian of Perry, in Maine, or in the Cat skill
group of New York.
In order that distinct notions may be conveyed as to the geological
horizons of the species, I may state that the typical Devonian or Erian
series of Canada and New York may be divided in descending order into--1.
The Chemung group, including the Chemung and Portage sandstones and
shales. 2. The Hamilton group, including the Genesee, Hamilton, and
Marcellus shales. 3. The Corniferous limestone and its associated beds.
4 The Oriskany sandstone. As the Corniferous limestone, which is the
equivalent of the Lower Carboniferous limestone in the Carboniferous
period, is marine, and affords scarcely any plants, we may, as is usually
done for like purposes in the Carboniferous, group it with the Oriskany
under the name Lower Erian. The Hamilton rocks will then be Middle Erian,
and the Chemung group Upper Erian. In the present state of our knowledge,
the series may be co-ordinated with the rocks of Gaspé, New Brunswick,
and Maine, as in the following table:
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account