NOTES ON THE TERTIARY GEOLOGY 59 



been long associated on solely conchological grounds. It is not insig- 

 nificant, either, that the fossil forms of this group found at the quarries 

 are of the small, ground-loving species which might be transported with 

 comparative ease by storms or other agencies, and not the large arboreal 

 species which may be supposed to be a more modern development on 

 the spot, being exclusively confined to these islands, while Auriculella, 

 Tornatellina, etcetera, the smaller types referred to, are much more widely 

 distributed. There can be little doubt from their remarkable develop- 

 ment that the AchatinellidaB reached these islands in Tertiary times, and 

 that their present luxuriance of form and color is the product of a pro- 

 longed period of local evolution. 



In the opposite direction from Diamond head, on the shores of Pearl 

 harbor, a very similar series of beds to those at the base of Diamond 

 head were exposed. The usually perpendicular face of the rock front- 

 ing the beaches usually rises about 30 feet above tide, but is largely reef 

 rock with shells and corals in abundance, well consolidated and with 

 several feet of alluvium above it. The strata are gently undulated, but 

 in no special or uniform general direction. About midway of the bluff 

 a layer of lava about 8 to 10 inches thick was noted, which had appar- 

 ently flowed over the reef rock below it,' and above which another series 

 of reef rock beds like the lower ones had formed. Ostrea, Monodonta, 

 Tellina, Avicula, etcetera, were noted in the reef rock, from which many 

 of the shells had been removed by solution. It should be noted that 

 the reef rock which underlies the western part of the city of Honolulu 

 and crops out at the water line in Honolulu harbor appears to be of an 

 extremely similar if not identical character. 



In the alluvium around Pearl harbor quantities of kitchen-midden 

 material was observed, chiefly Avicula and Ostrea sandwichensis, now 

 found living abundantly in the adjacent waters. 



About a quarter of a mile eastward from Waipio station on the Oahu 

 railway between Pearl harbor and Honolulu is a cut through a ridge of 

 earth, marl, and clay rising about 20 feet above the track and 35 feet 

 above tide. The beds dip seaward at a moderate angle. The section is 

 as follows : 



Red lava earth .... 3 feet. 



Marl with wave structure 8 " 



Clay layer with extinct oyster , 1 " 



Clay .' 2\ " 



Marl 1 " 



Clay 4 " 



Total above base. 



