346 Ernest W. iSheats : 



7. The mode of orip-in of the micro-pranite and its relation 

 to the diabase. 



8. The finding of corundum in the diabase and in the 

 selwynite. 



9. The possible mode of orig-in of the sehvynite. 



10. The eA'idence for the Lower Ordovician age of tlie cherts 

 and of the diabase series. 



DESCRIPTIONS OF PLATES XIV-XVIIL 



The uuml)ers of the rock sections have reference to the collections 

 at the University of Melbourne. All the rock sections were 

 photographed by Mr. H. J. Grayson, and were taken in ordinary 

 light. 



Plate XIV. 



1. Rock section 618 x 11 diameters. 



" Brecciated conglomerate," exposure in road running west 

 between allotments 3m and 3j, Knowsley East. Possibly a 

 coarse grained tuff. It consists of fragments of two types of 

 dialjasiu rock more or less altered to chert l)y secondary siliciti- 

 cation. 



2. Rock Section 545 x 11 diameters. 



Agglomerate of Photograph Knob, S. Heathcote. Larger and 

 smaller angular diabasic fragments are set in a tine grained 

 indurated ground-mass. 



3. Rock Section 576 x 1 1 diameters 



Boulder in foliated diabase of Red Hill, Heathcote. An 

 agglomerate consisting of large and small angular fragments of 

 diabase in a tine ground-mass. 



4. Rock Section 583 x 11 diameters. 



Diabase tuff, allotment 3(j, Knowsley East. The rock is 

 distinctly fragmental and contains secondary (juartz and secondary 

 felspars partially or wholly replacing disbase material. 



Platk XV. 



1. Rock Section 584 x 11 diameters. 



Bedded diabase tuffC?) Tranter's Paddock, M. of W. Knowsley 

 East. A silicitied cavernous rock, cavities originally occupied by 



