263 General Notes. [ March, 
directly formed ona former land surface, and we consequently 
find that it is invariably preceded by some more littoral quality 
of sediment. The nearer the original centre of depression or 
focus of subsidence, the older the green sands and Gaults must 
necessarily be; and the farther we recede from it in any landward 
ity in the fauna of each zone at any interval of distance, and it 
might maintain its distinct charcteristics over the most extensive 
areas, without, for all that, its contents having lived synchronous- 
slightest trace of the presence of angiospermous dicotyledons. 
Even the Gray Chalk and the Blackdown beds have only yielded 
conifers and a Williamsonia of Jurassic type. We cannot account 
for their absence by Supposing our area to have been isolated, 
for in the preceding Wealden period neither its fauna or flora 
ene PES 
