x _ JHE HAWKESBURY SANDSTONE. ae 
being removed either at the time the narrow gorges were cut 
by the retreating sea or subsequently by alluvial action.” 
None of the difficulties suggested by Dr. Darwin are met by 
is , and the absence of upheaval or marine remains is fatal 
toit. On the other hand, the aerial origin of the rock exactly 
i e facts. hese immense sandhills may have been 
always detached from one another, or if united, could have been 
easily cut into the gorges previous to their consolidation. No 
doubt they have become precipitous to some extent by weathering 
and was never much larger than we see it now. But the very 
7 a tite hardening of sandstone from drifting sand in Africa 
Siandstone _ Mr James Haswell gives an interesting account of 
A sand - 
he rain over the clay, and deposited on ledges formed by 
beds of shale, while the siliceous particles of which 
per was read at the Edinburgh Geological Society, January 21, 1869. 
i 
