02 GEOLOGY OF LOWER MESOZOIC ROCKS OF QUEENSLAXO, 



The marine fossils tix the age of the Lower Mesozoic of Western 

 Australia as Jurassic, and Etheridge refers those from the 

 Greenough River to the Oolite.* The Jurassic rocks cover a 

 large area in the Champion Bay district, near Geraldton, par- 

 ticularly between the Greenough and Irwin Rivers. According 

 to Gibb Maitland, they consist of "oolitic limestones, clays, sand- 

 stones (which are often ferruginous), grits, conglomerates, and 

 lignites."! Thev are horizontal or gentlv undulating, and their 

 thickness has been proved to the extent of 2,000 feet, by bores 

 in the Champion Bay district. 



From these rocks, Arber^ has described Otozamites Feist- 

 mmiteli, and a coniferous fragment from near Minginew: and he 

 has pointed out the resemblance of these to fossils from lalgai, 

 Darling Downs, and Rosewood, west of Rockhampton in Queens- 

 land. 



Examples of fossil plants in close association with marine 

 fossils are noted by Campbell. § Speaking of Mt. Hill.ji he says, 

 ''Fossil stems of a plant, apparently a species of Equisetacese, 

 and Palm or Otozamites stem-scales and pieces of wood occur in 

 the sandstones and grits of the north side." 



"A limestone band occurs at about 100 feet below the summit 

 of the hill, and can be well seen on the fence-line, 10 chains 

 west of the summit. Here, numerous Jurassic fossils occur in 

 an excellent state of preservation. On the ridge, also, extend- 

 ing north from the summit, there is a fossiliferous, fine-grained 

 sandstone." 



The results of Dr. Arber's examination of the plants froin 

 Minginew were apparently available to Mr. Campbell, since he 

 quotes (p. 58) Arber's conclusions, so it may be presumed that 

 the plants from Mt. Hill are similar to those from Minginew. 

 On Plate 5 of the same work, in the vertical section of the Don- 



* Geol. Surv. West Australia, Bulletin 36. 



t Geol. Surv. West Australia, Bulletin 50, p. 21. 



t Unci., Bulletin 36, p. 25. 



%Ihid., Bulletin 38. 



il Op. cit., p. 60. 



