284 



Christmas Island. 



numerous skeleton crj^stals of magnetite ; there is some glass}' base. 

 A few porphyritic crj^stals of pale purple augite and some 

 porphyritic felspars replaced by calcite occur. This basalt is 

 extensively exposed in the neighbourhood and is different from the 

 basalt above referred to as forming a dyke on the floor of the dale. 

 The soft rock (]^o. 318) forming the thin band separating the 

 basalt from the limestone above, and the massive limestone 

 (ISTo. 347), are described on p. 254. In both, the Lower Tertiary 

 type of Orhitoides is present. Unfortunately the relations of this 

 bed of ancient limestone were not worked out, because in the first 



^^^: 



Fig. 7. — Mouth of Sidney's Dale, West Coast 



place my stay in the neighbourhood was very brief, and in the 

 second without microscopic examination the age of the beds was 

 not recognizable. It will be noted that, as at Tlying Fish Cove, 

 this old limestone occurs at a comparatively low level, not being 

 more than about 250 feet above the sea. 



The volcanic rocks are exposed over a considerable area on the 

 east coast in the neighbourhood of the fresh-water stream and 

 waterfall marked on the Map. There they do not occur more 

 than about 150 feet at most above the sea- level; but towards the 



