1200 NOTES ON THE GEOLOGY OF BOWNING, N.S.W., 



Associated with these trilobites are the following : — A coral 

 which I take to be Petraia corniculum, Orthis testudinaria (?), 

 Leptaena, a large Pleurotomaria, Platyceras,sp., Cycloiiema, Stropho- 

 mena, an Orthoceras having a close affinity to 0. ccereesiense, and 

 Orthis biloba. Superimposed on this bed is an immense one 

 of shale with intercalated thin bands of flagstone. Its thickness 

 cannot be less than 1,300 ft. Towards the completion of the 

 bed the bands of flagstone and grit become more numerous and 

 thicker. Throughout this vast deposit fossils are either rare or 

 altogether absent. In the sandstone at the top I have obtained 

 the prints of shells like Orthis and Atrypa. The absence of 

 fossils from these shales would appear to have resulted from an 

 absence of life over the area they occupied at the time of their 

 formation, following upon the introduction of conditions unfavor- 

 able to organisms. The shales themselves are of a nature well- 

 fitted for the preservation of organisms, had they been present. 



From this bed we reach a series of beds that mark alternate 

 periods of marine disturbance and inactivity. These are most 

 likely sequences of considerable upheavals and subsidences of the 

 then sea- bottom. 



The first of these beds is one of conglomerate 20 feet thick. 

 The matrix is shale or mudstone ; some of the fragments are 

 corals and pieces of limestone showing markings of Pentamerus and 

 other shells. Then come 40 feet of soft shale followed by 25 feet of 

 conglomerate rich in fragments of encrinital limestone. On this 

 lie about 100 feet of sandstone of a flaggy character. Then 

 follow about 250 feet of shale containing numerous water-worn 

 stones, in parts almost a conglomerate. Near the top of the bed 

 are many thin bands of flagstone. Next is a bed of laminated 

 shale with bands of flagstone, 150 feet thick. On this rests a 

 coarse conglomerate 50 feet thick. Enclosed are boulders of 

 fossiliferous limestone. Succeeding this is a number of thin 

 strata of shale and sandstone alternately, whose united thickness 

 may be about 50 feet ; and then is reached the latest deposit. This 

 is a bed of coarse conglomerate that cannot have a thickness less 



