THE HAWKESBURY SANDSTONE. 107 
very much in the position of a guest unprovided with a wedding 
garment ; but I made a few notes at the time Mr. Tenison-Woods 
was reading his paper, on the copy he kindly placed at my disposal, 
and I may now, agg be allowed to refer to them. I think I 
was appealed to by Mr. Tenison-Woods in one or two cases, and 
Sse it will = best for me to comment upon those matters in 
e first ins 
If I fition aright, Mr. Tenison-Woods apnnes to me in 
reference to the composition of the cementing material of the 
oe etry sandstones. There is, I think, no iota that for the 
most part this material is of a felspathic nature. Even on the most 
S$ present in the sandstone were ies derived from the 
original granitoid rock, but others have doubtless been formed in 
eteretiy:: 
per. 
me next question was as to the origin of the masses and layer 
e in the Hawkesbury rocks. There can, I think 
te no a that the wv first put forth by Gustav one 
ae Ww suggested by Mr. Tenison-Woods as an explanatio 
Be ot the presence of the oxide of iron in these rocks, sudiciently 
_ counts both for the presence of, and for the peculiarities pre- 
- Sented na much of the ironstone, but not for all. Probably 
_ me of ‘the larger horizontal bands or layers have been formed 
Much as we see bog iron ore deposits accumulating at the present 
Pld The larger veins pei ch oe formed by infiltration, 
masses, have probably been. en formed as a amanek alah 
