GRADUAL DEGRADATION OF THE LAND. In this state they would gradually waste away beneath the ever-during influence of atmospheric causes, and the material being then carried down by the streams, through a series of caverns resembling those of which they once formed a portion, would be swept out into the ocean and deposited on sandbanks, to be raised again, at some remote epoch, a new continent, built up with the ruins of an ancient world. I subsequently, during the season of the heavy rains, remarked the usual character of the mountain streams to be that they rose at the foot of some little elevation which stood upon a lofty tableland composed of sandstone, then flowed in a sandy bed for a short distance and afterwards mysteriously sank in the cracks and crevices made in the rocks from atmospheric influences, and did not again reappear until they had reached the foot of the precipice which terminated the tableland whence they sprang; here they came foaming out in a rapid stream which had undoubtedly worked strange havoc in the porous sandstone rocks among which it held its subterraneous course. What the amount of sand annually carried down from the north-western portion of Australia into the ocean may be we have no means whatever of ascertaining; that it is sufficient to form beds of sand of very great magnitude is attested by the existence of numerous and extensive sandbanks all along the coast. One single heavy tropical shower of only a few hours' duration washed down, over a plot of ground which was planted with barley, a bed of sand nearly five inches deep, which the succeeding showers again swept off, carrying it further upon its way towards the sea. The space of ground covered with these columns gradually contracted its dimensions as we proceeded; the columns themselves became nearer and nearer to each other until they at length formed walls of cliffs on each side of us, and we finally reached a point where a single lofty pillar, standing in front of a dry cascade, formed the centre of an amphitheatre of sandstone. There was some water in a little natural basin at the base of the cliffs. I determined therefore to halt here for breakfast and, leaving the men at the foot of the cascade to prepare some tea, I clambered to its summit, and found myself on another tableland similar to that which I had just left, and covered in the same manner with natural columns. SANDSTONE CAVERNS.