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Bay beds cover a fairly large area of country to the south, in the neighbourhood of the coastline. They are seen to rest with a marked unconformity on the Permo-Carboniferous rocks of the Irwin River valley. They also extend northward, having been met with at Shark Bay and on the Gascoyne River, near the Kennedy Range. The Jurassic beds of the State are represented by oolitic limestones, clays, sandstones (which are often ferruginous), grits, conglomerates, and lignites. Some of the ferruginous sandstones contain abundant plant remains. As a rule the strata are horizontal or but gently undulating, and have probably been deposited along the then coast during a long period of depression. No estimate can as yet be made of the thickness of the Jurassic beds; they have, however, been pierced by four boreholes in the Champion Bay district which have proved the thickness to be not less than 2,000 ft. The plant remains occurring in these beds near Minginew seem to indicate that the beds are the equivalents of those at Talgai and Rosewood, in Queensland. The beds have yielded a rich Jurassic fauna, including the following:—
- Crinoidea. Pentacrinus, sp.
- Tubicola. Serpula conformis, Goldf.
- Bryozoa. Bryozoa, sp.
- Brachiopoda. Rhynchonella variabilis, Schl.; Rhynchonella solitaria, Moore.
- Pelecypoda. Area, sp. ; Alectryonia, Ostrea; Marshi, Sow.; Avicula œqualis, Moore; Avicula (MacCoyella) Barklyi, Moore; Avicula echinata, Sow. ; Avicula inœquivalvis, Sow.; Avicula Munsteri, Bronn.; Ctenostreon (Lima) pecteniformis, Schl.; Cucullœa infata, Moore; Cucnllœa oblonga, Sow.; Cucullœa semistriata; Cucullœa tibraddonensis, Eth. fils; Gryphœa, sp.; Hinnites, sp.; Lima Gordonii, Moore; Lima proboscidea, Sow.; Lima punctata , Sow.; Modiola Maitlandi, Eth. fils; Mytilus cf. gygerensis, d'Orb; Nucula, sp.; Ostrea tholiformis, Eth. fils; Pecten calous, Goldf.; Pecten cinctus, Sow.; Pecten cf. frontalis, Dum.; Pecten Greenoughiensis, Moore; Pecten valoniensis, Defr.; Pecten cf. vesicularis; Perna, sp.; Plicatula, sp.; Radula (Lima) duplicata, Sow.; Trigonia Moorei, Lycett; Trigonia costata, Clarke; Gresslya donaciformis, Phill.; Myacites liassianus, Gueust; Myacites Sanfordii, Moore; Pholadomya ovulum, Agassz; Pleuromya, sp.; Astarte apicalis, Moore; Astarte Cliftoni, Moore; Cardium, sp.; Cypricardia, sp.; Isocardia, sp.; Lucina, sp.; Opis, sp.; Panopœa (Glycimeris) ruyosa, Moore; Tancredia plana (?), Moore; Teredo (Pholas) Australis, Moore; Unicardiumo, sp.; Dentalium, sp.; Amberleya, sp.; Phasianella, sp.; Pleurotomaria Greenoughiensis, Eth. fils; Trochus; Turbo Australis, Moore; Turbo lœvigatus, Sow.; Cerithium Greenoughiensis, Moore; Chemnitzia, sp.; Nerinœa, sp.; Rissoina Australis, Moore; Actœon depressus, Moore.
- Cephalopoda. Nautilus perornatus, Crick; Nautilus sinuatus, Sow.; Ammonites lautus; Ammonites Walcottii, Sow.; Ammonites (Dorsetensia) Clarkei, Crick; Ammonites (Dumortieria) Moorei, Lycett; Ammonites (Macrocephalites) macrocephalus, Schl.; Ammonites (Perisphinctes) Championensis, Crick; Ammonites (Perisphinctes) robiginosus, Crick; Ammonites (Sphœoroceras) semiornatus, Crick; Ammonites (Sphoeoroceras) Woodwardi, Crick; Ammonites (Stephanoceras) Australis, Crick; Ammonites (Normannites) Australis, Crick; Belemnites canaliculatus, Schl.; Belemnites Canhami, Tate; Cythere corrosa, var. grossepunctata, Chap.; Cythere drupacea, var. fortior, Chap.; Cythere lobatula, Chap.; Cytheropteron Australiense, Chap.; Lotoconcha elongata, Chap.; Lotoconcha Jurassica, Chap.; Paradotorhyncha foveolata, Chap.
- Plantæ. Cf. Araucaria peregrina, Kurr; Cunninghamites Australis, Ten.-Woods; cf. Pagiophyllum, sp.; Otozamites Feistmanteli, Zigno; fern fronds and seed-vessels.
Glaciated Granite Boulder, embedded in blue clay, Irwin River
Cretaceous.—The presence of Cretaceous strata in Western Australia appears to have been known for pretty well half a century, having been first recorded by Mr. F. T. Gregory as occurring near Gin Gin. This same observer stated that the Cretaceous strata were the most extensively developed of the sedimentary rocks of Western Australia, and that the beds were very closely connected with the Jurassic rocks of the Greenough River. The boundary between the two series, however, has not as yet been satisfactorily traced.
Fossiliferous Cretaceous rocks have been proved in