Now, as we know not by what means the changes that have taken place on the earth's surface have been effected, and can only reason on them from analogy, it is to be feared we shall never arrive at any clear demonstration of the truth of our surmises with regard to geographical changes, whether extensive or local, since the causes which produced them will necessarily have ceased to operate. We cannot refer to the dates when they took place, as we may do in regard to the eruptions of a volcano, or the appearance or disappearance of an island. Such events are of minor importance. Those mighty changes to which I would be understood to allude, can hardly be laid to the account of chemical agency. We can easily comprehend how subterranean fires will occasionally burst forth, and can thus satisfactorily account for earthquake or volcano; but it is not to any clashing of properties, or to any visible causes, that the changes of which I speak can be attributed. They appear rather as the consequences of direct agency, of an invisible power, not as the occasional and fretful workings of nature herself. The marks of that awful catastrophe which so nearly extinguished the human race, are every day becoming more and more visible as geological research proceeds. Thus, in the limestone caves at Wellington Valley, the remains of fossils and exuviae, show that their depths were penetrated by the same searching element that poured into the caverns of Kirkdale and other places. They are as gleams of sunshine falling upon the pages of that sublime and splendid volume, in which the history of the deluge is alone to be found; as if the Almighty intended that His word should stand single and unsupported before mankind: and when we consider that such corroborative testimonies of his wrath, as those I have noticed, were in all probability wholly unknown to those who wrote that sacred book, the discovery of the remains of a past world, must strike those under whose knowledge it may fall with the truth of that awful event, which language has vainly endeavoured to describe and painters to represent. CHAPTER VIII. Environs of the lake Alexandrina--Appointment of Capt. Barker to make a further survey of the coast near Encounter Bay--Narrative of his proceedings--Mount Lofty, Mount Barker, and beautiful country adjacent--Australian salmon--Survey of the coast--Outlet of lake to the sea--Circumstances that led to the slaughter of Capt. Barker by the natives--His character--Features of this part of the country and capabilities of its coasts--Its adaptation for colonization--Suggestions for the furtherance of future Expeditions. ENVIRONS OF THE LAKE ALEXANDRINA.