DISCOVERY OF THE PROGRAMME. 97 



the North — is its counterpart, holding possession of the 

 northward prolongation of the same depression. Or, to 

 present the generalization in another form, the primordial 

 ridge, with its northeast and northwest branches, holds 

 Hudson's Bay in its embrace. The Appalachians and the 

 Rocky Mountains constitute the two branches of a second- 

 ary ridge, which do not meet toward the south. One of 

 these branches points toward the prolongation of Florida 

 and the peninsula of Yucatan, and the other toward the 

 prolongation of Mexico and Central America, with the 

 Gulf of Mexico — the Hudson's Bay of the South — occupy- 

 ing a depression between them. The space between the 

 primary and secondary ridges has two systems of drain- 

 age — one toward the north, and one toward the south. 

 Each system has two branches. In the northern system 

 the branches diverge from the lake region toward the 

 northeast through the St. Lawrence, and the northwest 

 through the McKenzie. In the southern system the 

 branches converge through the Ohio and the Missouri, 

 and discharge themselves by one outlet through the Mis- 

 sissippi. Thus the whole hydrographic and orographic sys- 

 tem of North America has been determined by the location 

 of these skeleton ridges — pieces of the framework which, 

 though for unnumbered ages they were yet unborn from the 

 deep, were nevertheless working out the configuration and 

 the topography of a continent. Indeed, as the secondary 

 pair of ridges was but a reduplication of the first, or Lau- 

 rentian pair, we find that the innumerable hydrograjDhical 

 and topographical features of our continent have taken 

 their point of departure from the Laurentian ridge as an 

 initial and germinal area. Finally, the trend and confor- 

 mation of our eastern coast are what has turned our "Gulf 

 Stream" to the northern shores of Europe, to mitigate the 

 climate of a little inhospitable island in the latitude of 



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