282 C//ristmas Island. 



550 (p. 246) and 562 (p. 243) were taken close to the underlying 

 volcanic rock, and 521 (p. 245), 551 (p. 248), and 646 (p. 246), 

 from pinnacles at the summit of the cliff (about 500 feet). It 

 will be seen that rocks nearly on the same horizon may exhibit 

 considerable diversity in their fossil contents, but since in most 

 cases the fossils were determined from a single section the diversity 

 may be more apparent than real. 



The whole of these Miocene Orbitoidal limestones were probably 

 deposited in shallow water on the summit and flanks of a sub- 

 marine bank. I never found Orhitoides on any rock more than 

 about 600 feet above the sea, although corals of Miocene age are 

 said to occur at much greater elevations (see p. 208). Before 

 these higher rocks could have been formed probably a certain 

 amount of subsidence had taken place. 



It will be convenient to describe here the northern end of the 

 Flying Fish Cove section (left-hand end of B in Fig. 2), although 

 in so doing it will be necessarj- to refer to some of the later rocks. 

 It has already been mentioned that at its northern end the cliff of 

 yellow limestone (marked B) becomes broken into minor cliffs (P), 

 which dip somewhat downward and are soon concealed beneath 

 a soil-clad talus slope. At a point sliglitly to the north of where 

 the main cliff of limestone breaks up, the basalt likewise disappears, 

 being partly concealed by soil, but mostly by a consolidated talus 

 composed of blocks of Miocene Orbitoidal limestone, with some 

 pebbles of volcanic rock. This forms a cliff (see N in section) 

 which can be seen to rest upon basaltic and trachytic rocks. At 

 its southern end, which is at a rather higher level than the main 

 face, the talus blocks arc angular, but throughout the greater part 

 of its extent they are perfectly rolled and rounded, and there can 

 be no doubt that we have here a section of an old beach which was 

 formed when the sea was 80 or 100 feet higher than now. Still 

 farther north this disappears under a coral-reef rock, probably formed 

 about the same time. Above the point in the section marked jN^-S 

 traces of beds of Miocene Orbitoidal limestone occur only about 

 200 feet up the cliff, showing that here also rocks of this age overlap 

 the earlier rocks as in the south. These in turn are concealed 

 beneath a great mass of cemented talus (M in section), which has 

 been cut back into a lofty cliff', M (80-100 feet in places). The 

 rocks comprising this talus include blocks of Orbitoidal limestone, 

 but seem to be mostly of later date. At its northern end this 

 cliff disappears beneath the limestones, forming the first inland 

 cliff at the Zigzag (see note on p. 263), and its foot is concealed 

 by a reef-rock (E) which partly covers the slope below it. In the 

 talus beneath the high cliff are numerous blocks of basalt and 

 palagonite tuffs, showing that the beds of these rocks are continued 

 to the northern end of the cove, where they also pass beneath 

 M and E. The lowest part of the section shows the face of the 

 sea cliff (D), consisting of late Pleistocene or possibly recent 

 limestones. 



