BIGSBY PALAEOZOIC BASIN OF NEW YORK. 445 



ing modifications, through countless ages, has become the tabernacle 

 of the highest order of existences. 



If we leave the Devonian for the Carboniferous system, the scene 

 is totally changed. In the latter we are presented with buried jungle 

 in layer upon layer, spreading over enormous spaces (1,000,000 

 square-miles in one body), distinctly of terrestrial origin, and inter- 

 mingled for the first time with freshwater deposits — unless Austen is 

 right in regarding some of the Devonian rocks as freshwater (Journ. 

 of Proc. Geol. Soc. xii. p. 51). Marine life is new, various, and 

 prolific. 



And thus we might advance along the whole series of sedimentary 

 rocks ; but this may suffice to show that systems exhibit differences 

 which are profound and universal, in comparison with which those 

 introduced with the Oneida Conglomerate were small indeed. 



The following paragraphs contain such a summary, however im- 

 perfect, of the opinions on this subject of Professors Rogers as is 

 compatible with the limits of this paper ; and they are an abstract 

 from the memoir by the younger brother, " On the Correlation of 

 the North American and British Palaeozoic Strata" (see Report 

 Assoc. Adv. Science, 1856). I shall endeavour to show my sincere 

 admiration of this valuable memoir by all the clearness and fidelity 

 I can command. 



Professor H. D. Rogers (loc. cit. p. 1 78) states that — 



1st. "The break or plane of discontinuity terminating the Ma- 

 tinal series, or Hudson-River group, exceeds all the others in the 

 Appalachian basin for the abruptness of the transition which it im- 

 plies in the organic remains, and in the magnitude of the crust- 

 movement*." 



2nd. (p. 186.) This Matinal break "revolutionized alike the entire 

 extent of the American and European areas, both in their inhabit- 

 ants and in their physical geography." It was a "stupendous 

 movement," "tremendous and nearly universal," p. 181. 



Evidence of the Physical Break. — 1. "From the Gulf of St. 

 Lawrence to the River Hudson (nearly 800 miles) this break is 

 marked by an unconformable interrupted sequence^, the Matinal 

 rocks [Hudson River group], highly inclined and folded, generally 

 supporting less inclined strata of the Levant [Medina Sandstone], or 

 some other middle palaeozoic formation." (p. 178.) 



* " The Appalachian palaeozoic strata contain several important planes of dis- 

 continuity. Tfiese are of very unequal magnitude, both geographically and strati - 

 graphically. ...The two most conspicuous of all are, that at the end of the Matinal 

 or Hudson-River period, and that at the beginning of the Vespertine or first Car- 

 boniferous age. Another, although materially less extensive, divides the Pre- 

 meridian or Lower Helderberg period from the Meridian or Oriskany Sandstone 

 age." Loc. cit. p. 178. (Post-carboniferous crust-movement is not adverted to.) 



f " Two sets of strata resting in contact," says H. D. Rogers, " may present not 

 only an absence of parallelism, but an omission of one or more intermediate for- 

 mations elsewhere existing. This state of things implies not only an inclining of 

 the inferior beds, but a lifting of them into dry land, with a lapse of time before 

 their immersion for the reception of the overlying deposits. Such a condition, 

 familiar as the commonest species of unconformity, may fitly be entitled an un- 

 conformable interrupted sequence ." (p. 178.) 



2g2 



