Dalrymple Bank, of the same nature, lies adjacent to Little Andaman, on the same side; but Invisible Bank, to the eastward, has depths of 17 to 50 fathoms, with a rock awash in the centre. This is of bluish-grey sandstone, so that the Bank, taking into account its irregular surface and the rapidly-increasing depths around, may be considered a submerged mountain-range, of the same formation as the oldest part of the Andamans--of which, Flat Rock, an isolated peak, rises alone above the sea. All these banks probably formed islands, or part of the Andamans, when the latter stood at a higher elevation than they do to-day. Throughout the Archipelago the scenery is of exceeding beauty. The picturesquely undulating surface is clad everywhere, save where artificial clearings have been made, with the most luxuriant jungle, for, situated within the tropics, with a fertile soil, and a climate that for two-thirds of the year is somewhat moist, the islands are covered from hill-top to sea-beach with an unbroken mantle of dense vegetation, rendered almost impenetrable by cane-brakes and undergrowth of rattans and other creepers. All along the shores are either stretches of yellow sand or brilliant green mangroves, and the seas round the islands are of the clearest water imaginable. The coast-line is everywhere deeply indented, and affords a number--most unusual for such a small group--of deep-water harbours and other anchorages, where complete shelter can be found for large ships in all weathers and seasons. The most known and the best--although Port Cornwallis is nearly as good, and has the advantage of being some twelve hours' steaming nearer to Calcutta and Rangoon--is Port Blair, where the Settlement has been placed; but on the same coast of Great Andaman are many others, the more important being, Macpherson's Straits, Shoal Bay, Port Meadows, Colebrooke Passage, and Stewart's Sound. On the west coast are situated, Port Andaman, Kwang-tung Harbour, Ports Campbell and Mouat, while in the Archipelago perfect anchorage is to be found either in Outram Harbour or in Charka-Juru,[85] Kwang-tung Strait, or Tadma-Juru. These are well distributed all along the coasts, and were the Andamans situated in some position of greater political or commercial importance, they would form an invaluable possession for this reason. As it is, the islands are exploited merely as a convict establishment--an Indian Botany Bay--and the only industry of any magnitude appertaining to them is that of timber, for which indeed the harbours are very convenient, as the forests worked are all in the neighbourhood of the seashore, or are so placed that after the trees are felled the logs can be hauled by elephants to the many creeks, and floated down to where the vessels engaged in the business are anchored.