500 GEOLOGY OF THE WESTERN DISTRICTS OF CANADA. 
as now prevails in the living creation.” Since Sir Charles wrote the 
above remarks it has been ascertained on a more minute investiga- 
tion that the number of species common to the Silurian rocks on 
both sides of the Atlantic is between thirty and forty per cent. ; and 
it is a most interesting fact that those which are identical are pre- 
cisely those which are found most widely diffused both geographically 
and in the order of superposition, and consequently seem to have 
been most capable of surviving many successive changes in the earth’s 
surface. 
Professor Sedgwick, at the recent meeting of the British Associ- 
ation in Aberdeen, in speaking of this order of geological forma- 
tions, characterized them by a figure quaint and graphic, though 
derived from modern feminine usages. He speaks of the lime- 
stone formations as a great girdle, or (in plain terms,) ‘“ hoop,’’ over 
which Dame Nature had spread her “ glorious palzozoic petticeat.”’ 
Certainly nowhere on the face of the globe has this skirt attamed a 
greater expansion, or been more gorgeously bedecked with the forms 
of ancient life, than in the locality now under notice. 
Details of the Rock Formations.—A very complete and most 
interesting section of the strata in a line running north and south, 
is afforded by the cutting on the line of the Niagara Falls and 
Lewiston Railroad, and by the ravine itself through which the great 
river flows.* ‘Taking the section at this most interesting locality as 
the basis of our future enquiries, I shall proceed to describe briefly 
the component parts, and shall take occasion while it is under review 
to recapitulate the arguments of Lyell and others, to prove the fact 
of the retrocession of the Falls from Queenston Heights to their 
present site. 
The strata in ascending order consist, first, of a soft red shaley 
and purely argillaceous marl, partially striped and spotted with green, 
‘seen in the bank of the river at Queenston and extending thence to 
Lake Ontario, and attaining a height of about one hundred and ten 
feet at the escarpment at Queenston. This formation, which is 
‘entirely devoid of calcareous matter, is regularly stratified, and inter. 
spersed with thin veins of a light green rock of similar composition 
though somewhat harder, the colors being evidently derived from the 
presence of iron. The traces of organic remains in this bed are 
* This section is represented graphically in Sir Charles Lyell’s First Visit to the United 
-States, 1841-2, Vol. I. page 36, to which we would refer our readers, 
