I became convinced, also, from observation of the country through which we had passed, that the sources of the Macquarie could not be of such magnitude as to give a constant flow to it as a river, and at the same time to supply with water the vast concavity into which it falls.

In very heavy rains only could the marshes and adjacent lands be laid wholly under water, since the evaporation alone would be equal to the supply.
The great plains stretching for so many miles to the westward of Mount Harris, even where they were clear of reeds, were covered with shells and the claws of cray-fish and their soil, although an alluvial deposit, was superficially sandy.

They bore the appearance not only of frequent inundation, but of the floods having eventually subsided upon them.

This was particularly observable at the bottom of the marshes.

We did not find any accumulation of rubbish to indicate a rush of water to any one point; but numerous minor channels existed to distribute the floods equally and generally over every part of the area subject to them, and the marks of inundation and subsidence were everywhere the same.