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



from the point of view of their economic value. The purity 

 of these limestones varies and is usually not of a very high 

 order as the following analyses taken from J. E. Oarne's 

 Report on the Limestones of New South Wales will show 

 (the small unimportant constituents are omitted). 



Analyses of Limestones 



CaC0 3 MgC0 3 Insoluble 

 Parish of Lewinsbrook (I)ungog Road 



two miles from Gresford) ... 78-03 2-10 17-32 

 Parish of Wallarobba (six mile peg 



Clarence Town-Glen William Rd.) 77*85 

 Parish of Wallarobba ditto... 

 County of Gloucester (two miles from 

 Dungog on Gloucester Road) ... 

 ditto ditto 



ditto ditto 



Parish of Horton, portion 53 

 ditto ditto 



ditto portion 18 



The impurities consist mainly of tuffaceous material, 

 coarse layers of which can frequently be seen in some of 

 the limestone beds. 



The Conglomerates. — The beds of conglomerate range 

 from a foot up to forty feet or even more in thickness. In 

 the smaller beds the pebbles range up to three inches in 

 diameter, but in the larger beds they range up to as much 

 as eighteen inches in diameter. The aggregate thickness 

 of the conglomerate beds in the Lower Carboniferous series 

 is not large, probably not more than 200 feet. The pebbles 

 consist mainly of quartzite, granite and quartz-porphyry. 

 Typical examples of these conglomerates occur on the 

 Wallarobba-Clarence Town Road (Parish of Wallarobba, 

 portions 182, 183), and also in the railway cuttings about 

 four to five miles east of Dungog. 



77-85 



3-08 



15-20 



4928 



1-88 



43-40 



82-06 



1-84 



12 



64-2.1 



1-99 



27-05 



87-59 



097 



9-10 



90-03 



0-48 



5-88 



72-35 



0-75 



20 18 



87-85 



1-05 



6-90 



