264 THE CAMBRIAN. Ibull. 81. 



slates into which they pass. After the colored mud of which these slates are com- 

 posed 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 gray sandy beds, and were evidently littoral species, as on 

 tracing the sandstones westward for half a mile they are found to chauge into a gray 

 slaty and pebbly deposit — evidently an old beach line — and finally disappear. 



Probably the physical condition of the St. Johu Basin at this early period was un- 

 favorable 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 chacteristic of the early Cambrian age are found. 



In Group d the slaty mass becomes quite fine and dark colored, but near St. John 

 is much affected by slaty cleavage, and the fossils are so much distorted, especially 

 in the upper part, as to be unrecognizable. 



In the beds of Division 2, a return of littoral conditions, and the influx of sand, 

 interfered with the prosperity of the crustacean fauna, and as in the lower sand beds 

 of Division 1, linguloid shells become the prevailing fossils. The Paradoxides which I 

 will describe in this article are those of the intermediate mud beds, now converted 

 into a mass of slaty rock (Division 1, c). 1 



On the evidence of the contained fauna, Mr. Matthew correlated the 

 fauna of the Paradoxides zone of the St. John group with that of the 

 Solva group of Wales, as denned by Dr. Hicks. 2 



In addition to the section as found at St. John there is to be added a 

 series described by Mr. Matthew, occurring below Division 1, on Hanford 

 Brook, in the eastern part of St. John County. In the report upon 

 the geology of southern New Brunswick, by L. W. Bailey, in 1865, this 

 mass of sediments was spoken of as the upper member of the Coldbrook 

 group and distinct from the St. John group ; it was subsequently joined 

 to the St. John group by Messrs. Bailey and Matthew in a report of 

 progress of the geological survey of Canada, 1870- 7 71, p. 59, because the 

 want of conformity existing between the two formations could not then 

 be established ; but it is now found that this series is unconformable 

 not only to the St. John group, but also, as had been previously dis- 

 covered, to the underlying Coldbrook group. 3 The section is as fol- 

 lows : 4 



Thickness 

 in feet. 



1 (a) Coarse purplish red Conglomerate, resting on an amygdaloidal greenstone 



(toadstone) of the Coldbrook group 60 



(b) Gray and purplish flags and sandstones with worm-casts, seaweeds 



(Palaeochorda and Buthotrephis), and numerous spicules of sponges.. . 70 



(o) Purplish red sandstones, with greenish layers. Remains of seaweeds 

 (Phycoidella), animal tracks (Psammnicbnites and Helminthites), 

 worm-burrows ( Arenicolites) etc 240 



'Op.cit.pp. 87-89. 



2 The geologic age of the Acadian fauna. The Primitive Conocorvphean. BritishAssoc. Rep., 54th 

 meeting, 1884, pp. 742-744. 

 * On a basal series of Cambrian rocks in Acadia. Canadian Record Science, vol. 3, 1888, p. 22. 

 4 On Cambrian Organisms in Acadia. Royal Soc. Canada, Trans., vol. 7, Proc, sec. 4, 1890, p. 138. 



