BY JOHN MITCHELL. 1197 



intrusion of the porphyry boss, and synchronously on the E. by 

 a similar intrusion. Among the results effected by the forces 

 that led to the formation of this, was probably the production of 

 Bowning Hill ; bat to enter into arguments to prove this would 

 at present be a digression. All the strata are well defined except 

 where severe plications have taken place. 



To estimate the thickness of the whole system with any degree 

 of exactness is at present not possible. 



Sections. — Starting from the junction of Limestone and Barber's 

 Creeks on the east, and proceeding nearly west to where the 

 G. S. Road crosses the porphyry ridge on the western side of 

 Bowning township, we obtain a section of the eastern division, or 

 what may more properly be termed a double section ; for, as stated 

 already, this embraces a synclinal basin ; and as one half of the 

 basin differs slightly from the other I shall give an ideal section of 

 each. The calculations as to thickness must be accepted as rough 

 approximations only. 



Commencing with the eastern section, a bed of coralline limestone 

 advancing a little beyond our eastern boundary, first claims 

 attention ; this is found to rest on a stratum of micaceous grit, 

 just beyond which the porphyry is exposed. 



This limestone alone would afford matter for several papers. Pro- 

 bably not another place can be found in the colony so fraught with 

 interest to the palaeontologist and geologist. What an accumulation 

 of ancient marine life is here displayed before our eyes ! And how 

 admirably preserved ! Everywhere corals of various kinds present 

 themselves, and commingling with them are numerous molluscs, 

 Euomphalus, Orthoceras, PenHmerus, Atrypa, Trochus, and other 

 genera being well represented. But to revert to the stratigra- 

 phical description of the bed. Throughout it has a stratified aspect ; 

 and at this point seems to be divided into two parts by a bluish 

 micaceous rock. The lower division lies in thin strata separated 

 from each other by thin layers of mudstone, thus giving evidence 

 of periodical invasions of sediment into a clear sea. Distributed 

 through the mudstone are calcareous nodules frequently containing 



