194 TRANSACTIONS OF THE [APR. 15, 
The thickness of this series is very great; at New River the 
section is over eleven thousand feet,* supposed to have been de- 
deposited in a gradually sinking area, bounded by the faults on 
each side. The immense erosion which this this series has suf- 
fered probably is the key to its more altered character, the rocks 
now at the surface having been very deeply buried. 
4, Etcheminian.t This is aseries underlying the Cambrian 
slates in most of their exposures, and unconformable both to 
them and to the Coldbrook rocks on which it rests. The rocks 
are wholly sedimentary in their typical exposures, but are be- 
lieved by G. F. Matthew to have been rapidly deposited by the 
working over of the softer voleanic beds, and to indicate a time 
of dying volcanic activity. There is reason to believe that part 
of the diabase which lies below the Cambrian at St. John is post- 
Etcheminian (possibly post-Cambrian as well). This series is 
considered by the last named author to be probably equivalent 
to the upper part of the Coastal; if so it has considerable directly 
volcanic material in it. 
To sum up, the pre-Cambrian near St. John includes the fol- 
lowing groups: 
A.— LAURENTIAN. 
1. Portland group, including Div. 2, with probably parts of 
Div. 1 in other localities than St. John. 
2. Intrusive granite and quartz-diorite; perhaps later than 
the position here assigned to it. 
B.—HUROnIAN. 
3. Coldbrook group or Div. 8, of volcanic rocks. 
4. Coastal group or Div. 4, of volcanic and sedimentary rocks, 
in its upper part probably equivalent to the next group. 
5. Htcheminian or Basal Series, of sedimentary rocks, under- 
lying the St. John group. 
6. Kingston group or Div. 5, of metamorphosed volcanics. 
Of very uncertain relations; may be post-Cambrian. 
Uprer LIMIT oF THE PRE-CAMBRIAN. 
The Cambrian is here considered to be limited by the uncon- 
formity at the base of the St. John group. The criterion 
given by Mr. Walcott for determining the base of the Cambrian, 
namely the lower limit of the Olenellus fauna, cannot here be 
applied, as Olenellus has not been found in New Brunswick, 
though a large pre-Paradoxidean fauna of very primitive type 
*G. F. Matthew, Can. Geol. Sur. Rep. 1887-8, p. 4E. 
+ Trans. Roy. Soc. Can. 1889, Sec. 4, p. 135. 
