Notes on the Mount Lyell mine

The western coast of Tasmania possesses but few indentations that can serve as reasonable harbours. Of these the most important one, commercially speaking, is Macquarie Harbour, on which is situated the port of Strahan. The country north of Strahan was subject to enormous fluctuations of level during early Silurian days, and deep seas alternated with wide, but shallow, lagoons, which in time rose into rugged hills, only again to disappear beneath the waters and lose their identity under the mud and pebbles that filled up the depressions and levelled the sea floor as with a smoothing iron. The mud and silt brought down by the ancient rivers, hardened into clay, slate, and schist, the pebbles were cemented into the ubiquitous conglomerate ; the blanketed sea floor, unable to lose its heat by radiation, sank deeper and deeper, causing the crumpling and upheaving that led to the last cycle of mountain-building, and the general configuration of the country became perhaps something as we now see it, though no doubt much lowered and scored, as well as filled up, by erosion and glacial action.