198 PROCEEDINGS OP SECTION C. 



made in regard to their age is, that rocks of a similar character 

 further north, are uncomformably overlaid by others containing 

 abundance of Upper Silurian fossils." Reference is probably made- 

 here to the Broken River, where rocks of a similar character are 

 overlaid uncomformably by a limestone (" Burdekin formation") 

 charged with fossils. The fossils, however, have turned out to be 

 Middle Devonian. 



The surmise that the Mount "VVyatt beds (which are uncon- 

 formably overlaid by the Star formation containing Lepidodendron, 

 say Carboniferous), and the others which Daintree classes with 

 them (and which are unconformably overlaid by the Burdekin 

 formation — say Middle Devonian) are of Upper Silurian age may 

 prove perfectly correct, but the question is decidedly an open one. 

 Their date may be anything older than Middle Devonian. 



As for Aplin's Lucky Valley rocks, they may very well prove 

 to be Carbonifero-Permian, like the Gympie beds. 



As, in all probability, the strata on the New South Wales side 

 of the border provisionally mapped as "Upper Silurian or Siluro- 

 Devonian," are continuous with those of Lucky Valley, we look 

 to the work of New South Wales geologists in that region tor 

 light on the subject, Mr. T.W. Edgeworth David, in his exhaustive 

 Memoir, " Geology of the Vegetable Creek Tin-Mining Field,"* 

 in referring to some Polyzoa, encrinites, Lamellibranchiata, and 

 univalves found by him in the Parish of Arvid, confesses (p Si) 

 that "these fossils prove the beds to be of marine origin, but do 

 not afford conclusive evidence as to their age." 



It seems to me that some vague general term such as Pre- 

 Devonian, would best express the present state of our knowledge 

 of a great part of the region hitherto regarded as Older Palaeozoic, 

 while another great portion will have to be handed over to the 

 Carbonifero-Permian. Lithological resemblance is a broken reed, 

 for the same conditions of aqueous arrangement of similar 

 materials, disturbance, pressure, and metamorphism, may and do 

 recur in widely separated times. 



The next group of stratified rocks whose horizon can be fixed 

 with some degree of precision, I have named the Burdekin 

 Formation. It represents the Middle Devonian, as is pretty 

 conclusively proved by its fossil contents. It is typically 

 developed in the Burdekin Valley, on the Fanning, and Broken 

 Rivers, and at the Reid River on the Northern Railway. The 

 fossiliferous beds are limestones, occasionally altei'ed to marble. 

 These are not greatly disturbed at the Burdekin, Fanning, and 

 Reid ; but on the Broken River they have a dip of about 

 60°. In the first-named places they rest directly, but 

 uncomformably on quartzites, slates, greywackes and shales, and 

 sometimes on granite. On the Broken River, diflerent conditions 



*Mein. Geol. Survey, N, S, Wales, Geology No. 1.1887, 4to., Sydney, f Government Printer) 



