1^6 REPORT — 1856. 



continuity, offering unusual facilities for the detection and tracing of their natural 

 horizons ; 'and Srdlj', on the fullness of the whole series of deposits as a record of 

 the physical and vital conditions of the ages which beheld their accumulation. The 

 American basin is not only more replete in specific forms than the pala-ozoic basin 

 of Europe, but more abundant in well-defined palseontological horizons. Geographi- 

 cally more continuous, it appears to be stratigraphically more expanded. From the 

 lowest platform of ancient life to the uppermost layers crowning the coal series, its 

 latest formation, the aggregate thickness of the strata is between 35,000 and 40,000 feet. 



To coordinate faithfully such distant affiliated systems of strata, each set of the rocks 

 to be compared should be classified in accordance with their own phsenomena, and 

 not upon any preconceived notions of their equivalency to the deposits of independent 

 districts assumed as standards ; nor should the classification rest solely on the rela- 

 tions of their organic remains, but should recognize equally their physical peculiarities 

 or composition, and the nature of the horizons dividing them. From a deferential 

 feeling among American palaeontologists towards their learned British brethren, 

 there has been, the author conceives, a disposition to apply prematurely a favourite 

 British nomenclature to the American strata, and this unphilosophical procedure has 

 tended to check that spirit of free inquiry which is indispensable to the perception of 

 the wider relationships and grander laws of creation. To apply to a large field of 

 nature in North America an interpretation expressed in a classification and nomen- 

 clature drawn from a distant region across the Atlantic, is to make one country a 

 standard for another ; whereas by the sanctions of inductive philosophy, each great 

 tract of creation must be its own exemplar, must itself furnish the measure of its own 

 phsenomena. In the universal federation of scientific intellect, no community or 

 school of thinkers, however able or authoritative within their own domain, can be- 

 come a supreme court of opinion in questions of a world-broad significance. 



Hitherto little has been done by the American and European geologists who have 

 attempted the arduous study of the American palaeozoic basin, to measure the de- 

 grees of relationship subsisting between its constituent formations, while those 

 affinities which have been examined have been almost exclusively palaeontological. 

 In this field all honour is due to the masterly labours of James Hall, and the in- 

 vestigations of M. De Verneuil, and of the lamented Daniel Sharpe. Other skilful 

 naturalists have contributed much to the definition of the American species ; Conrad 

 of Philadelphia, and William Salter of the Geological Survey of Great Britain, have 

 supplied many valuable determinations. Still there has been no systematic attempt 

 to explore the physical phsenomena, which are in beautiful coordination with these pa- 

 lseontological discoveries. While the fossils have been appealed to, as they should in 

 everv attempt at classification, the strata themselves have scarcely been interrogated. 

 In the present essay, the author's leading aim is to indicate the principal natural 

 planes which intersect the North American pateozoic strata and insulate them more 

 or less into formations, and to point out the relative magnitudes of the breaks of con- 

 tinuity, both as respects their geographical areas, and their greater or less distinctness 



in the vertical scale. But first it will be expedient to sketch the general limits of the 

 palaeozoic area of North America and of its chief subordinate basins. 



Paleozoic Basins of North America. 



We may estimate the surface originally covered by palteozoic sediments on this 

 continent at about five-sixths of all the land between the North Atlantic, Pacific, and 

 Arctic Oceans. These deposits are embraced in two great natural basins, bounded by 

 zones of the older crj'stalline rocks. By far the largest is a great interior basin, 

 spreading from the Appalachian chain to the Pacific mountains, and from the parallel 

 of 32" or 33° to the Arctic Sea and the Laurentian water-shed. This continental 

 palaeozoic area includes three wide fields of these rocks, partially separated superficially 

 by overlapping newer strata, but probably united underneath. These may be desig- 

 nated severally as the Appalachian, the Saskatchewan, and the Chippewayan basins. 

 The first extends westward from the Appalachian mountains to the eastern edge of 

 the sandy plains of Texas, Kansas, and Nebraska, and northward from the low cre- 

 taceous and tertiary plane fringing the Gulf of Mexico to the crystalline zone north 

 of the St. Lawrence and its lakes. The Saskatchewan basin, strictly a prolongation 

 of the Appalachian area, is a long palaeozoic belt stretching north-westward from the 



