the bottom rocks, in which, as being below the general level of the river bed, water remains after a flood, and in some of which it is maintained by natural springs; these are fresh or saline, too frequently the latter, according to the conditions in which they are found. The lower course of the rivers commonly opens into lakes, lagoons, or (as they are termed) estuaries, often formed by elevations or depressions in the rocks near the coast, and shut in from the sea by a bar of rock and sand, a passage through the latter being opened in time of flood, to be immediately closed by the action of the sea, when the force of the current of the river is no longer sufficient to keep it open. Some few of the rivers have, however, a stream continuous throughout the year, and of fresh water; these will be found on the South-Western and Northern coasts of the Colony. It will be seen that the main, as well as the lateral valleys of the river basins, are generally in the direction of the normal lines already indicated.
DESCRIPTIVE GEOGRAPHY.
When Captain Fremantle hoisted the British flag at the mouth of the Swan river, he took possession formally of all the land in the Great Island Continent now known as Australia not included in the Colony of New South Wales. Subsequently the Colony of Western Australia had its Eastern limit defined by the 129th meridian of longitude East from Greenwich, and in 1861 that also was made the Western boundary of the Colony of South Australia; the whole area to the West of that meridian is therefore within the limits of and subject to the
