Arkell.1956.Jurassic..

54°
CORDILLERAS OF NORTH AMERICA
of Canada (1953). For an up-to-date general picture of the geology see
Hanson & others, 1947.
TITHONIAN/PORTLANDIAN/KIMERIDGIAN
On Vancouver Island marine Lower Neocomian rests on an eroded
surface of a shale formation (with a median sandstone and siltstone member)
in which occur Buchia cf. russiensis (Pavlow) and B. cf. rugosa (Fischer).
These beds are believed to be 'Portlandian'. Buchia mosquensis (v. Buch)
also occurs in the lower Eldorado group near Lillooet, on the Fraser
River, and is believed to denote approximately the same age.
In the east, at Fernie, a gigantic ammonite has been found (Frebold,
m t n e D a s e
1953, p. 1239) °f ^e Kootenay Sandstone, which had usually
been considered Cretaceous. The ammonite, though poorly preserved,
can be seen from a photograph kindly sent me by Dr Frebold to be a
Perisphinctid, and appears to be a giant member of the Dorsoplanitinae.
The biplicate ribbing on its outer whorl is coarser than in most of the large
Titanites and allied genera of the Upper Portland Stone, but some parallels
can be found, e.g. audax Buckman (TA. vi, 1927, pi. DCCXVII), glottodes
(ibid, iv, 1923, pi. CDIII), zeta (ibid, v, 1923, pi. CDLII), okusensis
(ibid, v, 1925, pi. DLXX), or kerberus (ibid, vi, 1926, pi. DXX), which
provide a better match than the nearest Kimeridgian genera, such as
Pavlovia and Paravirgatites (ibid, iv, 1922, pi. CCCVIII) (Plate 26).
The basal Kootenay Sandstone usually passes down into the Jurassic
Fernie group, but locally there is an unconformity between them. The
upper member of the Fernie ('passage beds') consists of 30-60 m. of
unfossiliferous sandy beds which, from their stratigraphical position are
probably Kimeridgian or Lower Portlandian. In the west the Kimeridgian
may be represented by shales.
OXFORDIAN
In the west the shale sequence, with Buchia bronni and B. aff. khirgisensis,
etc., passes down into Oxfordian beds sometimes characterized
also by Buchia bronni but yielding ammonites. The latest assemblage
known is one of Cardioceras canadense Whiteaves, C. lillooetense Reeside
and C. whiteavesi Reeside, found at Big Creek, 90 miles NW. of
Lillooet. (For figures see Reeside, 1919, pi. xvii.) (For the dating
implications of these Cardioceratids see p. 548.) Traces of the same
assemblage are reported from Harrison Lake (with a Phylloceras)
in a 1500 m. sequence of argillite; from Vancouver Island; and from
about no miles NNW. of Hazelton.
In another area about 100 miles east of Hazelton, in central British
Columbia, records of Cardioceras (Scarburgiceras) aff. scarburgense (Y. &
B.) and C. (S.) aff. praecordatum Douville (Lord, 1948, pp. 23-4) indicate
that the Mariae Zone is represented.
In the east (Fernie) the Oxfordian is represented by Green Beds with
belemnites and gastropods (Frebold, 1953, p. 1238).
http://jurassic.ru/