If a corresponding height of similar strata was observable on the islands and on the main, it would amount to a proof that they were originally connected; but this proof was wanting. The same kind of strata appeared in both; but, as far as could be determined in passing hastily by, the necessary correspondence seemed to be deficient. They did not land upon either the islands or the main; but two kinds of rock, one with strata and the other without, were plainly discernible. That without strata formed by far the largest part; it appeared whitish and shining, was certainly a quartz, and probably a granite. The layers of the rock with strata were of various dark colours, and perfectly distinct.
It was evident, that land so much exposed to the violence of extensive oceans must have undergone some very material changes, by the incessant attrition of their vast waves. Two of the isles, either from this or a more sudden cause, have so far deviated from their centre, that their parallel strata form angles of between sixteens and eighteen degrees in one instance, and in another between twenty-five and thirty degrees, with the horizontal line. But it is difficult to explain, by the action of water, how a large block of the white stone without strata is caused to overhang an almost perpendicular corner of one of the islands, which beneath that block consists of the dark coloured stone lying in strata.
De Witt's Isles, (so named, probably, by Tasman) twelve in number, are of various sizes. The two largest are from three to four miles in circuit. Their sides are steep, but their height is inferior to that of the main. The largest is the lowest. The smaller isles are little more than large lumps of rock, of which that named by Captain Cook the mew stone is the southernmost. Their aspect, like that of the main, bespeaks extreme sterility; but, superior to the greater part of it, they produce a continued covering of brush; and upon the sloping sides of some of their gullies are a few stinted, half dead gum trees.
They could not account for the vestiges of fires that appeared upon the two inner large islands; the innermost in particular, which lay at some distance from the nearest point of the main, was burnt in patches upon different parts of it. It must have been effected either by lightning, or by the hand of man; but it was so much unlike the usual effects of the former, that, with all its difficulties, they chose to attribute it to the latter cause.
A great smoke that arose at the back of one of the bights showed the main to be inhabited; but they could not suppose the people of this place to be furnished with canoes, when those of Adventure Bay, in their neighbourhood, were unprovided with them. Nothing, therefore, was left to their choice, but to allow that they might transport themselves over, either upon logs of wood, or by swimming across: and, as the most probable reward of such an exertion would be the capture of birds, whilst breeding, or the seizure of their eggs, the utility of spreading fires in facilitating such operations is obvious.
The south cape may be easily distinguished from any other projection in its vicinity. Besides being the southernmost, it is a promontory making like a foreland, and sloping very gradually as it runs towards the sea, where it ends in a perpendicular cliff.
About sunset the fresh NW wind died away suddenly; and a strong squall from the westward, with thunder, lightning, and heavy rain, soon carried them round the south cape, and, by dark, brought them off what was formerly called Storm Bay, where they hauled to the wind with the sloop's head up the bay, intending, in the morning, to proceed by this Storm Bay passage into the Derwent river.
The night was squally, and by day light the next morning (the 14th), it was found that the vessel had drifted across the mouth of Storm Bay, or more properly Storm Bay Passage. Tasman's Head, its eastern point, bore NE distant three miles. Being too far to leeward to fetch up the passage, and the gale continuing, they bore away round Tasman's Head, and hauled up along shore for Adventure Bay.
Nothing remarkable was observed about Tasman's Head, except two small islands lying off it, at the distance of half or three quarters of a mile; and close to them were the two conical basaltic rocks named by Captain Furneaux the Friars. The vegetation upon the innermost of the two small islands had been burnt in a manner similar to that on the De Witt's isles. If it were possible to account for those fires in any other way than by the agency of man, it would be more satisfactory, than to suppose that people, always believed to be without canoes, had crossed over from a rather steep and rocky head, to an island equally rocky, but more steep.
Having passed Fluted Cape, a fine piece of basalt, and Penguin island, they fetched up under Cape Frederick Henry, the north point of Adventure Bay; but, as the wind blew strong directly off it, and the sloop was light and leewardly, they bore away round the Cape Frederick Henry, hauling upon the north side of it into the bay of that name, purposing to go into the Derwent river, discovered a few years since by Mr. Hayes, master of the ship Duke, of Bengal: but, finding that they were likely to lose ground by tacking, they stood into Henshaw's bay (so named by Hayes), and were greatly surprised to find that, instead of its being a mere shallow bight, as laid down in Mr. Hayes's chart, it extended many miles to the northward. The whole now bears the name of Frederick Henry Bay; that given by Hayes is lost. In this very extensive bay they remained a week, traversing and measuring various parts of its shores.