xlviii NOTES ON ZOOGEOGRAPHY. 



above which they are consolidated dune formation. Some of 

 these elevated beds have been referred to by Doctor Dall as 

 Pliocene. This determination was not based upon actual 

 determinations of fossils, but, I gather, from general con- 

 siderations. My collections of marine fossils around Pearl 

 Harbor and east of Diamond Head show only recent species, 

 and lend no support to the idea that the raised beds are older 

 than Pleistocene. 



The "raised reefs' I had opportunity to examine in west- 

 ern Molokai are consolidated calcareous sand. They are dune 

 deposits, as the irregular bedding clearly shows, although 

 they often contain sea shells, blown up from the shore. Not 

 much dependence is to be placed upon Hawaiian geology seen 

 from a steamer's deck. Upon the whole, it appears that in 

 Oahu there has been a very recent elevation, following a 

 subsidence of far greater amplitude. 



A good summary of the physiography and geology may be 

 found in the earlier chapters of Hawaii and its Volcanoes, 

 by Dr. Charles H. Hitchcock, Honolulu, 1909. 



Age of the land-shell beds. 



In the Islands the distinction between Pleistocene and 

 Holocene deposits is a real and necessary one, since human oc- 

 cupation brought in factors profoundly affecting the physiog- 

 raphy of the whole lower zone, or on some islands the entire 

 area. It would also be inexact to call the Holocene beds "re- 

 cent", though some of them are apparently of no great antiq- 

 uity. If the terms are used loosely* in this book it is because 

 not enough work has been done to fix the age of the various 

 dune deposits definitely. The Manoa, Kailua and Kahuku 

 bluff deposits, and the beds of Mana, Hawaii, seem to be un- 

 doubtedly Holocene. The dune-covered beds of northwestern 

 Oahu, those of Moomomi, Molokai, and those of the neck of 

 Maui (which I have not seen), are doubtless older than the 

 first group, but may possibly belong also to the early human 

 period. The human remains in the Moomomi dunes, however, 

 are probably intrusive. The land shell breccia and tuff of 

 Diamond Head and other tuff cones of the Kona side of 

 Oahu, are undoubtedly Pleistocene. 



