38 GEOLOGY OP LOWER MESOZOlC feOCKS OF QUEENSLAND, 



CfJ Summary ... ... ... ... ... ... ... ... 9o 



Geological History ... ... ... ... ... 96 



Pal.*:ogeographical Considerations ... ... 102 



SlTTVIMARY 11-2 



Explanation or Pl.\tes ... ... 115 



Introduction, and Scope of the Paper. 



In Eastern xA.ustralia and Tasmania there is no large develop- 

 ment of rocks of marine origin, representing deposition during 

 the period between the close of the Palaeozoic era and the 

 beginning of the Cretaceous period. During this interval, with 

 a single exception, the sediments deposited in this region were 

 of origin other than marine; the organic remains included in 

 these rocks consist for the most part of plants, but, in addition, 

 fish* and insects! are abundant on some horizons, phyllopods 

 are represented by Ef<theria, and pelecypods by Ufiio and Unio- 

 itella. The exception mentioned above is the upper portion of 

 the Wianamatta Stage in New South Wales; the top of this 

 stage is formed by a thickness of 100 feet of a calcareous rock, 

 which contains a fauna of Ostracoda and Foraminifera. This 

 fanna has been described by Chapman, whose conclusion regard- 

 ing the species is as follows : '• These undoubtedly represent a 

 brackish or estuarine fauna, having a curious intermingling of 

 Hhsetic and Lower Jurassic types, with others more properly 

 referable to the Upper Pakeozoic of Europe. ■':|: 



The term "Lower Mesozoic "' will be used throughout this 

 work for these rocks: the name "Trias- Jura ' has been generally 

 used, but it is not a suitable one, and we have not been, up to 

 the present, in a position to assign either a Triassic or Jurassic 

 age definitely to all of them. The name Lower Mesozoic may 

 be used generally to include the whole of these rocks, and to 

 refer to all the strata in Eastern Australia which were deposited 

 between the close of the Palaeozoic era and the be^innini; of the 

 Cretaceous period. 



"' Woodward, Mem. Geol. Surv. N. S. Wales, Palseontology, Nos.4, 9, 10. 

 t Etheridge and Olhff, ihid., Palaeontology, No. 7; Tillyard, Queensland 

 Geol. 8uiv., Publication No.2o3. 



J Records Geol. Surv. N. S. Wales, viii., p.33o, 1909. 



