88 G. F. MATTHEW ON ILLUSTRATIONS OF 



Division 0. a Red conglomerate—wanting at that part of the basin where this 
SECTION WAG MATE. eee cesse eos eer-heesress ee saree eect 
pb Redand green! sandy, slates ere eee Enr nee eee ere 150 
1. a Coarse grey sandstone or quartzite...........,.... D 0920000 0000 50 
b Coarse grey sandy slate (Linguloid shells)...................... 50 
ce Fine grey and dark grey slaty shales (Trilobites, etc)........... 25 
d Fine black carbonaceous slaty shales RON Soc To dia 75 5 
ÿ 2. a Dark grey slates with thin seams of grey sandstone............ 220 5 
b Coarse grey slates and grey flagstones . ......................., 200 3 
c Grey sandstones and coarse slates (Linguloid shells)......-..--. 130 Z 
4 3. a Dark grey, finely laminated slates...... ..2..:.cessceecss sevece 450 a 
b Black carbonaceous and dark grey slates, less fissile than the last. 300 
4. | Slates and flags resembling 2a and 2b mod shells)...... 800 
a 5. Black carbonaceous slate like 3 b (Orthids, Trilobites, etc)...... 450 
| 



Beyond Division 5 the beds are supposed to be repeated by an overturn, and have a 
width across nearly vertical measures of 3000 feet. Owing to this folding of the measures 
there is some uncertainty as to where the summit of the formation is, and the section given 
may not include the whole series of deposits. The faunæ of Divisions 2 and 5 are very 
imperfectly known, but there are much larger species of linguloid shells in these divisions 
than in Division 1; and the orthids of Division 5 are different from Orthis Billingsi of 
Division 1. 
The conglomerate at the base of the St. John group marks the time when the sea of 
the Acadian epoch invaded the valleys of the Huronian formation near St. John. No trace 
of life has yet been found in these coarse sediments, nor in the red and green slates into 
which they pass. After the coloured mud of which these slates are composed was deposited 
an abrupt change took place in the character of the deposit, and white sands were evenly 
spread over the whole basin. It is in the upper part of these sands that one meets with the 
earliest traces of primordial life. These first forms are linguloid shells of several genera. 
Such shells become more abundant in the upper part of the white and grey sandy beds, 
and were evidently littoral species, as on tracing the sandstones westward for half a mile 
they are found to change into a grey slaty and pebbly deposit,—evidently an old beach 
line—and finally disappear. 
‘Probably the physical condition of the St. John basin at this early period was 
unfavorable to the growth of the trilobites; but the land was sinking and an additional 
depth of water in this sheltered area soon encouraged the growth and multiplication of the 
crustacean fauna. As the sediment which settled from the sea-water in this deepening bay 
became finer, the remains of marine animals were preserved in greater numbers and variety, 
so that in the layers of fine slate in group c. of Division 1, many genera characteristic of the 
early Cambrian age are found. 
In group d, the slaty mass becomes quite fine and dark colored, but near St. John, 
a= - — 
