BY W. N. BENSON. 137 



scopic examination, proves to be composed entirely of fragmental 

 quartz and albite. Agglomeratic rocks of a rather different 

 nature, composed of fragments of keratopbyre, magnetite-kerato- 

 phyre, and dolerite in a matrix of keratopbyre, lie to tbe west of 

 a great band of jasper, which forms the ridge of the hill between 

 Silver Gully and Pipeclay Creek. This agglomeratic rock appears 

 to be rather of the nature of an intrusive igneous rock, filled 

 with cognate inclusions. 



The jasper has the same peculiar feature as that of the Hyde's 

 Creek complex. The scree from the ridge covers the easterly 

 slope, and through it there appear two small areas of vesicular 

 quartz-magnetite-keratophyre like that north of jasper at Hyde's 

 Creek. 



Below the limestone on Pipeclay Creek, there is another 

 intimate association of agglomerate and massive igneous rock (in 

 this instance a porphyrite) in which it is difiicult to distinguish 

 between an agglomerate, and an igneous intrusion tilled with 

 inclusions. This has not been investigated yet. East of this 

 mass, and extending from Silver Gully, across Pipeclay Creek 

 towards Cope's Creek, is a band of very siliceous keratopbyre. 

 It is a grey rock, often containing small felspar-phenocrysts, very 

 vesicular, and often amygdaloidal. The long amygdules are filled 

 with calcite, or frequently with quartz or agate, while the micro- 

 scopic features of the rock show further signs. of the action of 

 silicifying solutions. Occasionally the rock is traversed by veins 

 of red jasper. In this case, also, there is no line of contact with 

 the sediments exposed, nor is it obvious that the mass is an 

 intrusion. It is very uniform in character, has a width of from 

 fifty to a hundred yards, and is not associated with any obviously 

 ejectmental deposits. 



Petrographical Characters. 



In the foregoing, the Devonian igneous rocks were classed 

 into the dolerite-spilite series, the keratophyres, quartz-kerato- 

 phyres, magnetite-keratophyres, and the variolites of Munro's 

 Creek. They were briefly described in Part iii. of this series, but 

 a more detailed account is now possible, and some modification 

 of the former statements must be made. 



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