In rocks of this age in America, after long search and much slicing of limestones, I have hitherto failed to find any decided foraminiferal remains other than the Tudor and Madoc specimens, which may be of this age. They are laminated forms resembling Eozoon, but I have reason to believe that their minute structure more closely resembles that of Cryptozoon, though it is somewhat obscure. If these are really Huronian and not Laurentian, the Eozoon from this horizon does not sensibly differ from that of the Lower Laurentian.
We are indebted to Mr. Matthew, of St. John, New Brunswick, who has so greatly distinguished himself by his discoveries in the Cambrian of that region, for some remarkable additions to the contemporaries of Eozoon. One of these is a laminated body, like Eozoon in its general appearance, but growing in crowded masses which by mutual pressure become columnar ([Fig. 57]). In the best preserved specimens each layer seems to consist of a thin lamina separated from its neighbours by a finely granular mass, traversed by innumerable irregular tubes. This recalls the structure of Cryptozoon of Hall, which, as we have seen, is found in pre-Cambrian rocks in Colorado, and abounds in the Upper Cambrian in New York, in Minnesota, and in different parts of Canada, but Archæozoon differs in its form and habit of growth. If the Stromatoporæ of the Ordovician and Silurian are hydroids, this may also be the case with Cryptozoon; but so far as its own structure is concerned, it approaches most nearly to the fossils known as Loftusia in the Carboniferous and later formations, and these are generally regarded as Foraminiferal. We may thus have another giant Foraminiferal organism which contributed to the building up of rocks in the Laurentian seas.
Fig. 57.—Archæozoon Acadiense, Matthew. Diagrammatic transverse and longitudinal sections of a small specimen.
Specimen in Peter Redpath Museum.
Pre-Palæozoic Rocks of Southern New Brunswick,
as tabulated by Matthew:—"
ARCHÆAN
| EOZOIC | Thickness Feet. | |
Coastal series (or system), 1872.— | 10,000 | |
Coldbrook Series (or System), 1865.— | 15,000 | |
Upper series (or system) of Laurentian, 1872. Upper division.—Argillites, limestones, graphitic shales. Fossils. In upper part of the upper limestones of the South basin, fragmental Eozoon, observed by Sir J. W. Dawson in specimens sent him. In middle of upper limestones in Middle basin, spicules of sponges. In graphitic shale of South basin, spicules of Halichondrites graphitiferus. In lowest limestone of the Middle basin, the reef of columnar fossils described as Archæozoon | 750 | |
Middle division.—Quartzites, silicious schists, Fossils Cyathospongia (?) eozoica near the top of this division | 450 | |
Lower division.—Limestones and gneisses. No Fossils known | 260[41] | |
Lower series of Laurentian.— | ? |
[41] The above thicknesses are on the authority of Dr. L. W. Bailey. Report Progress Geological Survey Canada, 1879, pp. 10, D. D., and 21, D. D. Dr. R. W. Ells in the same Report, p. 6, D., describes these rocks, sixty miles east of St. John, as one system, with a thickness of 14,000 feet.
Fig. 57A.—Archæozoon Acadiense, Matthew.
Horizontal and vertical sections of a group of specimens, reduced.
(From Photographs.)