Arkell.1956.Jurassic..

to the north of the Geraldton outcrops. The beds are considered to be
Upper Jurassic (Teichert, 1952, p. 131).
AUSTRALIA 461
North-West Cape
A massive development of marine Upper Jurassic and Callovian has
been proved to underlie the later surface rocks near North-West Cape.
Deep borings made in 1954 in the Cape Range by the West Australian
Petroleum Co. proved over 1300 m. of dark grey micaceous siltstone.
FIG. 73.—The freshwater Jurassic rocks of Australia, after David & Browne, 1950.
Remains of ammonites and belemnites in core samples sent me in 1955
indicate the presence of Berriasian or Tithonian, ? Oxfordian and Lower
Callovian assemblages from 4293 to 6536 ft. below surface. (See fig. 72).
Jurassic freshwater beds of Australia
Except for these fringes in the west and north-west, Australia was
continental during the Jurassic. Almost half the total area of the present
continent, however, was covered by a vast system of freshwater lakes
('Lake Walloon'), having a total surface area of perhaps 300,000 square
miles. The areas submerged are shown approximately in fig. 71. In
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