Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/31

Rh bank is composed of alluvial deposit, and is timbered almost to where the end finishes off in a clump of reeds; the width of these natural embankments, which separate the waters of the Mitchell River from Jones's Bay on the north and Eagle Bay on the south, does not, on the average, exceed ten chains.

I believe these banks have been formed partly by the ploughing action of the floods in the soft deposits at the mouth of the river, and partly by the deposition of sediment carried down where the current is checked by the reed-beds, and also by similar causes whenever the floods rise over the bank itself.

I have reason to believe from personal observation, as well as from information derived from boatmen, fishermen, and others navigating the lakes, that these great expanses of scarcely more than brackish water are extremely shallow, and are only navigable in the deep channels which traverse them. These, it seems to me, foreshadow future river-channels so soon as the lakes shall have been silted up by the river-deposits or laid dry by further gradual elevation of the coast-line.

It seems to me that we see in these lakes and in the channels through them the former condition of the river-valleys, and that the present courses of the rivers are probably not due so much to the erosion by them of channels in the alluvial bottoms of the valleys as to their still flowing in channels which were formed under estuarine or lacustrine conditions.

The rivers of Gippsland are liable to frequent floods, which are due either to heavy rains, generally from the eastward, or to the melting of snow accumulated during the winter months on the mountains, or to both causes combined.

During the past five or six years these floods have been exceptionally frequent and severe. Neither the oldest white settlers nor the oldest aboriginal natives remember floods of like frequency or magnitude.

I have observed during the time mentioned that the beds of the torrent portions of the rivers appear to have been deepened, as in the upper waters of the Mitchell, Nicholson, Tambo, or Buchan rivers. The course of the rivers in the flat country has been completely changed within certain limits, as at Stratford and Bruthen. In steep mountain country the hillsides have been stripped of soil to the level of high-flood mark, as at the Turnback crossing of the Snowy River. Large trees which stood on islands have either been torn down and swept away, or stripped of their bark by drifting timber. All these various effects I have specially noticed in the Deddick River.

The amount of deposit carried down by these rivers is, of course,