Page:Handbook of Western Australia.djvu/27



As the horizontal contours of any portion of the earth's surface must depend on the vertical, or, in other words, the various features which are marked on the map—the coast line, plains, rivers, vallies, lakes, hills, mountains, &c., being consequent on the different elevations of the various portions of the surface above the level of the sea; and as those elevations are the results of geological formation, a general knowledge of the geology of any country is the best introduction to a knowledge of its geography.

The geology of Western Australia is in its general features very simple. Upon an undulating surface of granitoidal rocks, passing, as is common elsewhere, into gneiss and other forms of metamorphic rock, have been deposited strata, for the most part horizontal, of