264 E. 0. Tin el e: 



interesting questions with regard to the age of the limestone. 

 The specimens identified show such an extremely reniaikuble asso- 

 ciation of genera that better preserved material is urgently 

 required before safe conclusions can be drawn. At present, 

 however, it can be stated that on stratigraphical evidence one 

 ■would be strongly inclined to group the limestone wnth the 

 Upper Ordovician slates. 



(4) The Jaspergid Slates. 



These rocks are well exposed in several places, notably on tlie 

 Dolodrook River, below Garvey's Hut, as shown on the map, and 

 again on a spur to the south of the same hut. 



Until last January the age of these rocks had not been fixed, 

 and as it seemed to be a growing custom to consider all black 

 jasperoid and cherty rocks in the Lower Palaeozoic areas of Vic- 

 toria as Heathcotian, it was advisable to test the case in the 

 Dolodrook area. 



Careful search in this district showed clearly that here these 

 rocks must be grouped with the normal black slates of Upper 

 Ordovician age, for the characteristic gTaptolites were found 

 throuofhout the series, and highly silicified bands were found 

 clearly interbedded with the normal slates. 



Thin sections of various grades of the indurated slates showed 

 fine examj>les of various stages in the silicifieation. All showed 

 evidence of extreme pressure developing a schistose structure 

 marked by undulating lines, too black and dense to be deter- 

 mined, but containing a minute micaceous mineral. Abundant 

 lenticles of secondary quartz and chalcedony make up the 

 greater part of the rock. 



(6) TiiE Graptolite Slates. 



There is now really no need to separate these from the 

 jasperoid slates. They are all one series, exhibiting different 

 degrees of induration and silicifieation. They form the prevail- 

 ing rock surrounding the serpentine belt, and afford graptolites 

 in numerous localities. These fossils have been described in a 

 paper by Dr. T. S. Hall. Many outcrops show intense contor- 

 tion and crumpling, so that observations of dips are generally 



