NIAGARA FALLS AND VICINITY 3 1 



derberg range, which culminates in southeastern New York in the 

 high plateau of the Catskills. The Allegany plateau is everywhere 

 much dissected bv streams whose gorges have made the scenery of 

 southern New York famous. 



We have now seen that the topographic features of the Niagara 

 district are arranged in a series of six east and west extending belts 

 of alternating lowlands and terraciform elevations. The lowlands 

 are the Ontario, Tonawanda-Chippewa, and Erie, the uplands are 

 defined by the Niagara escarpment, the Onondaga escarpment and 

 the hills of southern New York which constitute the northern edge 

 of the Allegany plateau. The northern boundary of this belted 

 country is formed by the old Canadian highlands. 



We must now briefly consider the various strata of which the 

 area under consideration is constructed, their origin, and the man- 

 ner in which the topographic features of this region were produced. 

 A brief review of the table of Paleozoic strata, given on pages 20 

 and 21; will be helpful to an understanding of the succeeding pages. 



Development of the Paleozoic coastal plain 



The Laurentian old-land is composed of rocks older than the 

 Cambric period of the earth's history. These are largely of igneous 

 origin, and such as were originally sediments have generally suf- 

 fered much alteration through heat, pressure and other causes, and 

 in most cases have assumed a more or less crystalline character. 

 Though many of these pre-Cambric rocks may show apparent 

 stratification, the present attitude of the beds does not often bear 

 a close relation to their original condition. Indeed, these ancient 

 rocks are generally much disturbed, their beds folded and flexed, 

 and their laminae much contorted. Nor do the layers of the pre- 

 Cambric rocks bear any normal relation to those of later date, the 

 two series being wholly discordant with each other. The older beds 

 are much worn, vast portions of the ancient folds having been swept 

 away by erosion, and on the truncated edges of the remaining por- 

 tions the newer strata were deposited in an essentially horizontal 

 position. This unconformity of relation between the newer and 

 older strata is a marked feature wherever the two series are ex- 



