597 
the cataract a precipice, beneath which occurs the shale, also 80 feet 
thick. 
4. The Protean group.—Under the water at the base of the Falls 
crop out the higher beds of this formation, the name of which has 
been derived from the variable nature of its component strata. In 
the district more particularly described in this paper the group is 
only 30 feet thick, but farther to the eastward it attains thrice those 
dimensions. On the Niagara it consists of 25 feet of hard limestone, 
resting on 4 feet of shale; while at Rochester, eighty miles to the 
eastward, it comprises, among other beds, a dark shale with grapto- 
lites, or fossiliferous iron ore, and beneath them a limestone full of 
Pentamerus oblongus and P. levis, considered by Mr. Conrad to be 
one species. On account of the occurrence of this shell, the whole 
of these strata have been separated from the Niagara series, 
5. Ontario group.—About half a mile below the Falls the upper- 
most beds of the Ontario group crop out. At the whirlpool they 
have a thickness of 70 feet, and at Queenstown of 200, but to the 
latter dimension must be added 150 feet of inferior beds, exposed be- 
tween Queenstown and Lake Ontario. The entire group consists of 
1. Red marl with beds of hard sandstone in its 
Met, CUUISIOM ee cece oi sia vee ce Pe ics eee 
2. White quartzose strata, so hard as to form 
at Queenstown a ledge projecting beyond > 25 — 
Pic taGe Othe) CSCanpMenity srs i: ae crs er. 
3. Red marl and sandstone.................. 250 — 
70 feet, 
Other divisions of the group, coneealed beneath the waters of the 
lake, may be studied in the cliffs of its eastern and north-eastern 
shores. 
' Mr. Lyell next proceeds to give a brief account of the geographical 
distribution of the formations cr groups. ‘The strike of the beds be- 
ing east and west, and the dip very slight towards the south, the 
sections exposed along the Niagara afford a key to the structure of 
a large portion of the State of New York, the same deposits having 
been traced eastward through a region 40 miles in breadth by 150 
in length, and westward to a much greater distance. ‘The Helder- 
berg and the Niagara limestones constitute platforms which ter- 
minate in parallel escarpments, from twenty to twenty-five miles 
apart, about sixteen miles of the intervening space being occupied 
by the saliferous group. The Helderberg escarpment, to the east 
of Buffalo, is 50 feet high; but in the neighbourhood of the Nia- 
gara it has been denuded and is half buried beneath drift ; it is how- 
ever resumed in Upper Canada, and eastward it may be followed to 
the river Hudson. The Niagara limestone escarpment presents at 
Lewistown and Queenstown a cliff 300 feet high, which may be 
traced eastward nearly 100 miles and westward for a much greater 
distance. The limestone series, however, constitutes only the up- 
permost third of the escarpment, the remainder bemg composed of 
the Protean and the Ontario groups ; the whole section being as fol- 
lows :— 
3D 2 
