PROCEEDINGS OF SECTION C. 181 



Round Island. — This island is small and some what round in shape, 

 and lies between Woody Island and the mainland. 



In all of these islands, with the exception of Round Island, one finds 

 a characteristic shape which has been described above and which 

 is undoubtedly due to their having a backbone of sandstones and cherts, 

 the latter being derived from a silicification of shales of undoubted 

 marine origin. 



In the case of Round Island, however, one finds freshwater beds 

 of shales and sandstones and an absence of the cherts characteristic 

 of the other islands. 



Stratigraphy. 



Woody Island. — ^This Island is made up of a marine and a fresh- 

 water series of beds, with cappings of recent conglomerates, breccias, 

 and limestones. 



There is a perfectly conformable passage from the marine series 

 up into the freshwater series. At North Bluff, on the N.E. side of 

 the island, one finds interbedded with the marine beds freshwater 

 sandstones and shales at least 100 feet thick (see Plate VI.). The general 

 strike of the beds, both freshwater and marine, is from 40° to 45° W. of 

 N,, while the dip is always in a direction from 50° to 45° W. of S. 



Sharp junctions between the two series of beds may be seen on the 

 N.W. part of the island east of Datum Point (see Plate V.), and on the 

 S.W. of the island, due S. of Middle Bluff Lighthouse. The same beds 

 at the junction can be recognised in both places. 



The dip of the beds at the junction E. of Datum Point is 70°, 

 dir. 50° W. of S., whereas at the other exposed junction the dip is 20°, 

 dir. 50° W. of S. 



No change in dip or strike of the beds at the junction points can 

 be detected, and everything points to a perfect conformity. 



Owing to the amount of material washed down off the slopes 

 no exposures can be picked up on the island along the line connecting 

 the two junctions, but the line joining them up corresponds exactly 

 with the general strike of the beds. 



There is, then, no doubt of a perfectly conformable passage from 

 the marine to the freshwater beds, and of the main mass of the marine 

 beds underlying the freshwater beds (Plate VI.). 



Marine Series. — These consist of sandstones, calcareous sandstones, 

 shales, and cherts, and they all contain abundant fossils of a shallow 

 marine type. 



At North Bluff the interbedded freshwater beds of sandstones 

 and shales have an absence of marine fossils but an abundance of plant 

 remains, which are, however, unrecognisable. At this point the beds 



