Geology. 287 



just describerl. This is a much altered i>lassy basalt with small 

 porphyritic felspars aud augites. The base has been for the most 

 part altered into a yellowish and greenish bn)wn palao-ouite-like 

 substance which contains many microliths of plagioclase. There 

 are some vesicles filled with concentric layers of a transparent 

 substance showinsz; a black cross between crossed nicols. Tlie lower 

 part of the bed is divided into fairly regular hexagonal vertical 

 prisms, the summits of which have been broken into small angular 

 fragments and recemented with crystalline calcite, the resulting 

 rock having a remarkable api)earance owing to the sharp contrast 

 between the black basalt and the white lime. This extends up 

 the cliff for about 40 feet, and is in some places capped by a foot 

 or two of a tine- grained brown rock, apparently an ash, and on 

 the top of the cliff there is a thick bed of red palagonite tuff. In 

 a cliff a little to the south a clean section of the basalt shows 

 that it is divided into four or five beds separated by indurated and 

 brecciated limestone. The whole is covered by a conglomerate of 

 blocks of limestone, some of great size, probably a consolidated 

 talus from the inland cliffs. 



South of Steep I'oint the base of the sea cliff is formed of basalt 

 divided into hexagonal columns, in one case apparently curved. 



Still farther south there are extensive exposures of basalt, which 

 may be distinguished at a long distance from the summits of the 

 inland cliti's by the great size of the sago-palms {Arenqa listeri) 

 which grow upon them ; in this locality volcanic rocks may occur 

 up to 4U0 feet above the sea. 



In some localities on the east coast the Miocene Orbitoidal lime- 

 stones are magnificently developed. The most notable exposure is 

 near jS'orth-East Point, where the whole of the first inland cliff for 

 more than half a mile consists of limestones of this age, crowded 

 with the characteristic fossils. This cliff is about 250 feet high, 

 and it appears to have been formed by a slipping away of a portion 

 of the eastern flank of the island. A little farther south a much 

 more extensive slip has taken place, giving rise to a cliff upwards 

 of 500 feet in height and consisting apparently almost wholly of 

 Miocene rocks. Towards the summit (about 400 feet) is found 

 the rock which Messrs. Jones & Chapman have described above 

 (No. 955, p. 255) as a breccia of fragments of Orbitoidal limestone 

 cemented by recent reef material, but I am inclined to doubt 

 whether the brecciation and recementing of the rock may not both 

 be of Miocene date. 



The base of these cliffs is concealed by a talus of great blocks 

 and also in the northern part by comparatively recent reef-lime- 

 stones which once formed a narrow fringing reef along their foot ; 

 it cannot therefore be seen whether here, as at Flying Fish Cove, 

 these Miocene limestones rest on a volcanic basis or not ; but since 

 in the immediate neighbourhood pebbles of basaltic rock occur 

 in the shore platform, and since at the same level aud only about 

 a mile further south the basalts and tuffs are present and of 



