Proceedings of the British Association. 365 



nomena of the British chains. He lastly endeavored to show 

 how, in many cases, a reversed dip might be produced after the 

 first protrusion of a central granitic axis. Prof. Sedgwick con- 

 cluded with a merited compliment to the American nation for the 

 elaborate surveys they had published, of which the present me- 

 moir was an example ; the facts of which must, in the end, 



serve along with similar phenomena to form the base of a legiti- 

 mate theory. 



Dr. Dale Owen communicated a memoir on the Western States 

 of North America : it was illustrated by maps, sections and dia- 

 grams of fossils. The grand feature of the country is the Illi- 

 nois coal-field, equal in extent to all England, separated from an- 

 other coal-field, that of the Ohio, by an axis of much older rocks. 

 The object of the memoir was to identify those lower rocks with 

 the systems which supported the carboniferous series of England.* 



Mr, Phillips compared the extreme simplicity in the succession 

 of strata and distribution of organic remains observable in these 

 districts of North America under consideration, with the great 

 breadth occupied in Ireland by calcareous beds of the carbonif- 

 erous era, where a similar deficiency existed in the middle and 

 superior members of the series. This particular American series 

 was deficient in tertiary rocks ; its cretaceous system was defi- 

 cient in white chalk ; the Neokomian beds and the oolites were 

 all absent ; the lias and new red sandstone were also deficient ; 

 and then came the coal, succeeded by limestones, sandstones and 

 shales, and these by altered strata and granite. The analogy be- 

 tween the American cretaceous deposits and those of Europe was 

 very striking j though specific differences did exist between the 

 fossils of the two countries, yet these differences were very slight, 

 merely marking the effect of local influence : regarded as a group, 

 the two deposits were identical, and there could be no question 

 of their contemporaneous deposition. Passing from the cretaceous 

 deposits, we did not meet with the series which in Europe suc- 

 ceed to them, but we passed suddenly to the coal formation, with- 

 out a trace of the fossils of the intervening beds ; whilst the 



| 



plants of the American coal measures, although they might differ 

 specifically from those of Europe, belong to the same leading 

 groups,— Stigmaria, Pecopteris, Neuropteris, Sigillaria, &c. In 



This memoir was subsequently read before the Geological Society of London. 



