211 



and even there they are turning red in places. The red color is 

 of course simply due to the reduction of the iron in the sediments 

 from the state of glauconite to a higher state of oxidation by the 

 atmosphere, where they are not kept moist by the tide waters. 

 It should be noted that the strata are remarkably dry, not a drop 

 of water trickling down on any part of the cliffs. 



A thin layer of ironstone is found coating some of the fallen 

 boulders, as well as some of the rocks still in situ. The iron 

 carbonate of the strata has been converted into oxide, and has 

 segregated or blistered out at the surface. This segregation of 

 iron-oxide, though perhaps difficult to explain, is not uncommon. 

 Without pursuing the subject further in this paper, we may 

 instance the red sands of Arabia, which were found by Mr. J. A. 

 Phillip to be coated with iron in a similar manner. According 

 to his analyses, the iron in the external coating of the grains 

 almost equalled the total amount contained in them."^ 



Incidentally, reference has been made to the rugged limestones 

 to the north-east of Bird Rock. Not only do they appear there, 

 and also at the mouth of Spring Creek, but they crop-out again 

 on the southern slope of the dome at Rocky Point, and continue 

 on still farther to the south west. They are full of polyzoal and 

 coral remains, and contain also echinoderms, brachiopods and 

 fragments of pectens. They are most unpromising-looking rocks, 

 and by all previous observers have, we believe, been regarded as 

 the topmost layer of the fossiliferous strata. From their com- 

 mencement at Spring Creek they continue with a slight inter- 

 ruption to within a short distance of Bird Rock, when the cliffs 

 almost suddenly change their character and become rich in 

 gasteropods and lamellibranchs. The actual junction of the two 

 sets of strata is concealed by fallen masses of clay, which cover 

 the face of the clitf. On the southern slope, as previously stated, 

 the echinoderm-rock underlies strata containing the usual 

 bivalves, but sparingly distributed. This rock, though softer and 

 less rugged than the polyzoal limestone on either flank of the 

 dome, certainly represents it. The latter was followed step by 

 step from Rocky Point in a north-easterly direction until the 

 bivalves showed a good way up on the cliffs. A few yards farther 

 on the strata had assumed the usual appearance, with bands of 

 bivalves, &c., and this was maintained until the polyzoal rock 

 was again encountered on the other side of Bird Rock. Judging, 

 however, from some fallen boulders on the beach a little to the 

 south of the middle of the section, certain portions of the more 

 elevated strata, while not devoid of gasteropods, etc., evidently 

 contain more than the usual proportion of echinoderms and 



*Q. J. S. S., vol. XXXVIIL, p. 112. 



