THE NIAGARA LIMESTONE 123 



surface slope is toward the north. It results that the various formations 

 reach the surface in parallel belts running east and west. Some of the 

 harder rocks find topographic expression in lines of cliff facing north- 

 ward, and this is especially true of the Corniferous limestone and Niagara 

 limestone, each of which is a resistant sheet interleaved between thick 

 formations of more yielding material. The Niagara cliff is the more 

 northerl}^ and runs parallel to the lake at a distance of about 10 miles. 

 The Niagara limestone is here 190 feet thick. Only a small portion 

 is exposed in vertical section along the cliff; the remainder is beveled 



South North 



Figure 1. — Profile and Section in western Neio York from the Corniferous Terrace to Lake Ontario. 



Vertical scale five times the horizoutal. Distance represented, 25 miles. Baseline at sealevel. 

 C, Corniferous limestone. N, Niagara limestone. L, shore of lake Ontario. 



off SO as to present an inclined plain 8 or 10 miles broad. This plain 

 descends southward, the southern boundary of the outcrop being 50 to 

 75 feet lower than the northern. The configuration of the rock surface 

 is in general concealed by drift, but a few prominences are exposed. The 

 outlines of these trend in various directions and do not conform to the 

 direction of ice motion. 



MIDDLEPORT 

 GAS PORT ^^ — -^-^'''Z^^J^^^^^^^V^^^''' 



Figure 2. — Map of Niagara Limestone and Escarpment. 



The localitjf is near Gasport and Middleport, New York. The full line shows the boundary be- 

 tween the Niagara limestone (south) and the Niagara shale (north). The broken line shows the 

 position of the Niagara escarpment where not coincident with the boundary of the limestone. 



The northern boundary of the formation and the associated cliff were 

 examined in detail through a space of 30 miles. For the greater part of 

 this distance the rock is exposed to view in the crest of the cliff, but else- 

 where it is more or less buried, and observation was less satisfactory. A 

 notable, and to me surprising, feature is the absence of the limestone 

 from the cliff through considerable spaces. From Middleport westward 

 for a distance of 7 miles only about one-half of the cliff is capped by lime- 

 stone, the remainder exhibiting the underlying shale. The accompan}^- 

 ing map, figure 2, shows the relation of the limestone to the cliff in this 



