BY THE REV. J. MILNE CURRAN. 803 



parallel and wavy ridges, left by the last ripple of water, will play 

 an important part when the origin of the sandstones comes to be 

 dealt with. If a single impression on either side of the median 

 line be substituted for the double mark in Fig. 113 b. of Prestwich's 

 Geology, Vol. II., a faii'ly correct idea may be formed of the 

 track-marks at Pulpulla. 



Upper Silurian 



Rookery Limestones. 

 West Grenfell Sandstones. 

 Balowra Limestone. 

 Hermitage Limestone. 



On the Rookery Station, twenty-two miles south-east of Cobar, 

 limestone is abundant. The beds are highly inclined with a 

 westerly dip. Wherever the limestone is not altered to a 

 saccharoid texture, it is found to be more or less fossiliferous. 

 Mr. Etheridge determined the following species from this locality : — 

 Chonetes sp.; Stroipliomena corrugatella, Davidson; Sioirifer plica- 

 tella, Linn. In addition to these I have found fragments of a 

 gasteropod resembling Loxonema, Orthoceras, and some indetermin- 

 able corals. The Rookery beds will yield an abimdant harvest to 

 a systematic search for fossils. Spirifer plicatella, it need hardly be 

 stated, is one of the characteristic fossils of the Wenlock, which 

 have become familiar through the cuts in Geological Text-books 

 (see Prestwich, Vol. II., Plate ill., fig. 10). It has not been found 

 before in N. .S. Wales, but is recorded from the Upper Silurian of 

 Kilmore Creek, Victoria. We may with some show of reason 

 refer the Rookery limestones to the Upper Silurian. 



The fossils may be found in the limestone of the Homestead 

 paddock, a few hundred yards to the north-west of Mr. Hurley's 

 house ; and in limestone on the station generally. 



On Mount Grenfell Station, about tweuty-four miles north-west 

 of Cobar, fossils are found in water-worn boulders over many parts 

 of the run. In situ, they are abundant at the new dam thrown 



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