308 C. A. SUSSMILCH AND T. W. E. DAVID. 



field Sandstone of the Lower Marine .Series, about 1000 

 feet below the base of the Greta Goal Measures at West 

 Maitland. The lower bed of tillite, separated from the 

 upper by about 90 feet of marine mudstones, rests without 

 any visible break or unconformity on dark shales, not on the 

 calcareous shales with gypsum, and bun-shaped nodules of 

 argillaceous limestones. Up to the present no fossils have 

 been discovered in the strata immediately underlying the 

 lower tillites. Beneath these grey argillaceous beds and 

 separated from them by an immense unconformity are the 

 Pre-Oambrian gneiss, schist and granite. 



Before considering the palasontological evidence as to 

 the age of the Irwin tillites reference must be made to the 

 Wooramel, Gascoyne, Minilya Rivers area. Mr. A. Gibb 

 Maitland's accounts of this area are to be found chiefly in 

 the two papers below. 1 Mr. Maitland gives a section (op. 

 cit., p. 11) showing the boulder bed, three feet in thickness, 

 underlying thick marine limestones. In the boulder bed 

 itself the following fossils are recorded (op. cit., pp. 14, 15). 



Hexagonella dendroidea Hudleston sp. 



Pleurophyllum austral e Hinde ; fragments of crinoid stems. 



and Polyzoa. 

 Spirifera Hardmani Foord. 



„ lata McCoy. Reticularia. 



,, lineata Martin sp. 

 Athyris Macleayana Eth. fil. 

 Chonetes Pratti Davidson. Productus. 



ef. P. tenuistriatus Foord. 

 Aviculopecten tenuicollis (Dana). 



1 Bull. No. 33, Geol. Surv. West Australia, "The Gascoyne Ashburton 

 and West Pilbara Goldfields," by A. Gibb Maitland ; also Eep. Aust. 

 Assoc. Adv. Sci., Adelaide, 1907, pp. 131 - 157. 



