522 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 16, 



of mica. The Bluff, a bold promontory on the opposite side of the 

 Straits, is composed of the same rock. In Stewart's Island this rock 

 is penetrated and altered by the intrusion of trap-dykes, of from 1 to 

 3 feet in width, passing through it, and ramifying as they ascend. 



To the northward of the Bluff an extensive plain stretches along 

 the sea-coast in a N.E. direction, and also to the N.W. as far as 

 Jacob's River, where the level country ends. The coast then assumes 

 a high and broken outline, the hills rising to an elevation of from 

 2000 to 3000 feet. Long tracks of elevated land run parallel with 

 the coast, and have the appearance of horizontal ridges ; behind 

 them singular dome-shaped hills arise, as if from inland plains or 

 valleys ; in some places the top of the dome is, as it were, cut 

 smooth off, leaving a flat tabular top. 



Beyond Windsor Point, and towards West Cape, the coast assumes 

 a different character, consisting of long low spurs of yellow stratified 

 sandstone, stretching seaward. The cliffs are in some places 500 feet 

 high, and at Preservation South Head, North Entrance, the forma- 

 tion is very well seen. The sandstone cliffs at Preservation Harbour 

 very much resemble those in the neighbourhood of Sydney and New- 

 castle, N.S.W., and contain coal. Rounding the South Head, a 

 broken rocky point appears, which exhibits a good section of the 

 formation, consisting of strata of quartzose grit, fine sandstones, shale, 

 coal*, and a bluish trap-rock with a slaty fracture, — all dipping 

 N.E. at an angle of 45°. The faiotest traces, however, of coal are 

 only to be seen here ; apparently the thinning-out of the uppermost 

 seams. Proceeding along the beach about 300 yards, after passing 

 over great masses of sandstone, intermixed with water-worn boulders 

 of a coarse flesh-coloured granite, a sandy beach is reached, and 

 there the seams of coal are found running transversely across the 

 sand from low-water mark towards the cliffs of sandstone which form 

 the sea-face of the island, Preservation Island as it is called, on 

 which the coal shows itself. What the thickness of these beds may 

 be, where they are covered and protected by the overlying sand, 

 there are no means of judging ; where they show themselves on the 

 beach and sides of the cliffs, they appear to be merely the thin- 

 ning-out of the beds or a basin-shaped deposit of limited extent, for 

 at the North Head, distant about one mile, they again show them- 

 selves in the same way. It is thus seen that as they rise on the cliffs 

 on either side, they become gradually lost in the thinnest veins. 



The first vein of any size which occurs on the beach is of a variable 

 thickness, of from 6 to 10 inches. The shales which accompany the 

 coal are of the same average thickness ; they are hard and contain 

 vegetable impressions. Above them lies a considerable thickness of 

 grey pepper-coloured sandstone, all overlaid by a coarse quartzose 

 grit, in which are imbedded ironstone nodules, with fragments and 

 thin seams of carbonaceous matter. Between the several seams of 

 coal there is a thickness of about 30 yards of shale and sandstone. 



No limestones were found, nor fossiliferous strata of any kind, 

 whereby to determine the age of the deposit. 



* For the character of this coal see further on, p. 528. 



