of the Falls of Niagara. 551 



2. White quartzose strata, so hard as to form~| 



at Queenstown a ledge projecting beyond > 25 feet 

 the face of the escarpment J 



3. Red marl and sandstone 250 ... 



Other divisions of the group, concealed 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 or 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 being composed of 

 the Protean and the Ontario groups ; the whole section being as fol- 

 lows : — 



1 . Niagara limestone, lower beds 30 feet. 



2. Niagara, or Rochester shale 80 ... 



3. Protean beds 30 ... 



4. Ontario group : red marl, with hard beds in! 7ft 



the upper part J 



5. : quartzose grey sandstone,! 9 _ 



with Lingular, &c J 



6 : red marl 100 ... 



335 feet. 

 Though only the lower beds of the Niagara limestone occur in the 

 escarpment at Lewistown, yet, in consequence of the gentle rise of 

 the strata to the north, the summit of these lower beds is at a higher 

 level than that of Lake Erie. The whole of the Niagara platform is 

 covered irregularly with hillocks of drift, beneath which the lime- 

 stone is polished and furrowed. 



From the foot of the Queenstown escarpment to Lake Ontario, a 

 distance of six or seven miles, is a low tract, consisting of sandstones 

 belonging to the Ontario group, and dipping like the preceding beds 

 slightly to the south. 



A section which accompanied the memoir to illustrate the pre- 

 ceding details corresponds, the author says, in all essential particu- 



