102 THE TRIAS OR NEW RED SANDSTONE. 



and tlie older metamorphic rocks may be studied, and specimens of 

 their characteristic minerals obtained. Hence, at various times, this 

 locality has had the reputation of producing useful minerals of dif- 

 ferent descriptions. The latest instance of this led to the formation 

 of a copper mining company in London, which, after a very fair 

 promise of success, was broken up, owing to a deficiency of the ore, 

 which on trial was found by no means to warrant the reports that had 

 been published respecting it. The trap which forms the summit of 

 Gerrish's Mountain is a huge bed resting on red sandstone, on which 

 at the high cliff of Indian Point it is seen to rest. The trap at this 

 place is traversed by a number of narrow and irregular veins of 

 magnetic iron ore, mixed with the gray sulphuret and oxide of copper. 

 Specimens of this substance were sent to me, many years since, by 

 the late George Duncan, Esq. of Truro, and I was somewhat struck 

 by the singular appearance and composition of the mineral, which 

 was stated to be found in great quantity. From my knowledge of 

 the superficial character of the trap, and the smallness and irregularity 

 of the metallic veins found in it, I rather discouraged Mr Duncan 

 from speculating on it, though some specimens seemed sufficiently 

 rich to be useful as copper ores. It appears, however, that a very 

 favourable report was given by an English mining engineer, and 

 operations were commenced in consequence, but were soon abandoned. 



Between Five Islands and Swan Creek, ten miles distant, an excel- 

 lent coast section, rising in many places into lofty cliffs, shows the 

 New Red Sandstone and Trap, as well as the underlying Carboniferous 

 strata. As this section is an interesting specimen of the complicated 

 appearances that may result from the eruption of volcanic rocks 

 through stratified deposits, I shall give a detailed description of the 

 arrangements observed. 



At the mouth of Harrington River, opposite the Five Islands, the 

 Carboniferous rocks approach the shore very closely ; and as seen in 

 the west side of the river, consist of black shales and dark-coloured 

 sandstones with Cordaites and other fossil plants. They dip at high 

 angles to the south, and are met by the New Red Sandstone dipping 

 gently to the southward. The sandstones of the newer formation 

 here contain little conglomerate, and are variegated by numerous 

 greenish bands and blotches. They occupy the shore for some dis- 

 tance, and then contain a thick bed of trap conglomerate, consisting of 

 large partially rounded fragments of amygdaloidal and compact trap, 

 united by a hard brownish argillaceous cement. At a short distance 

 westward, another bed of trap conglomerate of the same kind appears 

 in the cliff. It is overlaid by a bed of dark clay, filled with angular 



