GEOLOGICAL REMARKS. 
227 
Mr. Oxley, on the Lachlan, was only 500, there being a still 
greater fall of country beyond these two points. The maxi- 
mum height of the fossil bank was 300 feet ; and if we 
suppose a line to be drawn from its top to the eastward, that 
line would pass over the marshes of the two rivers, and would 
cut them at a point below which they both gradually di- 
minish. Hence I am brought to conclude that in former 
times the sea washed the western base <)f the dividing 
ranges, at or near the two points whose respective elevations 
I have given ; and that when the mass of land now lying 
waste and unproductive, became exposed, the rivers, which 
until then had pursued a regular course to the ocean, having 
no channel beyond their original termination, overflowed 
the almost level country into which they now fall ; or, fil- 
ling some extensive concavity, have contributed, by succes- 
sive depositions, to the formation of those marshes of which 
so much has been said. I regret extremely, that my defect- 
ive vision prevents me giving a slight sketch to elucidate 
what I fear I have, in words, perhaps, failed in making suf- 
ficiently intelligible. 
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, whe- 
ther 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 
Q 2 
