244 Transactions. 



The strongest supporter of a trans-Pacific continent is Dr. Baur, of 

 Chicago. He deals with the matter, largely from a biological standpoint, in 

 an extremely important paper on " The Origin of the Galapagos Islands," 

 pubHshed in the " American Naturalist," vol. xxxi. After a thorough exami- 

 nation of the distribution of numerous families and genera he concludes 

 that the Pacific islands are the remains of a former Pacific continent ; that 

 this continent existed till just before Miocene times. 



It is thus very apparent that there is a strong consensus of opinion 

 among leading zoologists that a Pacific continent once existed, the prin- 

 cipal disagreement being in the matter of boundaries. While Hedley would 

 restrict it to his Melanesian platform, Pilsbry and probably Von Ihering 

 would extend it as far as Tahiti and the Marquesas, and Hutton and Barn- 

 would make it stretch as far as South America. 



It is not my intention to discuss further the biological side of this ques- 

 tion, but to collate the geological evidence afiorded up to the present as to 

 the probability of the existence of such a mass of land. The evidence as to 

 the continental nature of each group of islands over the site of the hypo- 

 thetical continent will be briefly considered. 



Kermadec Islands. 



Owing to their peculiar position half-way between New Zealand and 

 Tonga, the Kermadecs possess a special importance in this matter, so that 

 any geological evidence which they afford is of great value. 



A suggested continental connection for them, based on geological evi- 

 dence, was made by Professor Thomas in his paper " Notes on the Eocks of 

 the Kermadec Islands " (Trans. N.Z. Inst., vol. xx, p. 311, 1888). In describ- 

 ing the specimens collected by Mr. Percy Smith he notes the occurrence of a 

 granite, but suggests that it may have come to the islands in the ballast 

 of some ships. Present results show that this view cannot be accepted. 

 While the main mass of the Kermadecs is composed of volcanic rocks con- 

 sisting chiefly of augite hypersthene andesites of somewhat acid character, 

 olivine augite andesites of basic character, and acid basalts, there occur 

 in the tuffs on the north side of Sunday Island numerous boulders of horn- 

 blende granite. These boulders also occur scattered about the island, and 

 one specimen came from a block situated at a height of 1,600 ft. Pro- 

 fessor Thomas's suggestion as to the " ballast " origin of these boulders is 

 therefore untenable, and his first hypothesis of the island forming part of 

 a continental area seems to be perfectly sound. Mr. Ohver did not find 

 the rock in position, but from the occurrence of many fragments it is evident 

 that plutonic rocks must be at a very shallow depth below the volcanic 

 covering, and may even yet be discovered in situ in the group. When the 

 small extent of the visible plutonic basement of volcanic islands Uke the 

 Auckland Islands is considered, it is extremely Ukely that a mask of volcanic 

 rocks may completely cover a granite formdation of the Kermadecs. But 

 the existence of the fragments in such numbers undoubtedly shows its pre- 

 sence in close proximity. The condition seems very like that which would 

 obtain if the Bounty Islands, which consist of a few granite islets and rocks, 

 only a few feet above the sea, were to become the scene of volcanic activity, 

 and were buried by fragmentary matter and flows of lava. The Bounties 

 contain only one fresh-water alga, and a few low forms of animal fife be- 

 sides the birds and seals which visit them. Should such an island be built 

 up, and become large enough to allow vegetation to flourish, then it would 



