64 E. 0. Teale: 



The trilobite rocks which at the Dolodrook and Heathcote provide 

 evidence of the Cambrian age, are absent in the Howqua, but the 

 field evidence shows that the diabases and cherts are low down in a 

 series of sediments, in the higher portions of which Lower Ordo- 

 vician fossils have been discovered. 



At Heathcote the succession from Cambrian to Lower Ordovician 

 appears to be conformable, the diabases and cherts being on an 

 undoubted Cambrian horizon. It appears reasonable here to in- 

 clude the similar rocks of the Howqua in the same period. 



With regard to the associated Lower Palaeozoic sediments, a. 

 lithological and fossil discordance on the western and eastern sides 

 of the main diabase is noted and discussed. Upper Ordovician 

 and possibly Silurian fossils are restricted to a small area on the 

 western side, close to the diabase. The rest of the sediments on 

 this side have so far yielded no fossils. They consist largely of 

 slates, sometimes black, often talcose and chloritic, and usually 

 highly contorted. Chertification is slight. On the eastern side the 

 Profospongia cherts appear to be conformably in contact with the 

 diabase. They form a well defined zone, which is follow^ed by a 

 series of alternating sandstones and olive green phyllitic slates so far 

 unfossiliferous over a great range of thickness. Higher in the 

 series, thin bands of black slate carrying Lower Ordovician fossils 

 are interbedded with strata of this type. No Silurian fossils have 

 yet been obtained on this side. Some which are possibly Upper 

 Ordovician occur. 



The general structure of the area is somewhat obscure, but a 

 faulted anticline with the Upper Ordovician or Silurian included 

 as a small nipped-in piece, is suggested, as illustrated in the sketch 

 section. 



The upper Palaeozoic rocks are briefly referred to : 



The rocks of Devonian age are : — 



1. Dacite Porphyry. 



2. Granodiorite. 



3. Diorite. 



Those of Lower Carboniferous age are : — 



1. Conglomerates. 



2. Rhyolite. 



3. Pebbly and flaggy sandstones. 



4. Purplish shales. 



