Association of American Geologists and Naturalists. 241 



Alleghany depositSj where the " troubles'''^ of the European mines 

 are, in a great measure, unknown. At the same time, the dis- 

 turbed anthracite region of central Pennsylvania, contains in its 

 fractured and folded mountains and strata, a lucid record of the 

 operations of fire, both in its mechanical effects and in the de- 

 bituminization of the coal, which, without any material differ- 

 ence in its geological relations compared with those of the bitu- 

 minous coal into which it insensibly graduates as we proceed 

 westward, has yielded up its bitumen by expulsion or decomposi- 

 tion, urged by invasions of heat from below. 

 ~ The Silurian formation of Mr. Murchison, so well described 

 by him as it exists in Wales, is developed on an amazing scale, 

 and with strongly marked features, in western New York, 

 and generally in the Western States, while the tertiary, which, 

 in other countries, Mr. Lyell has illustrated with unequalled co- 

 piousness and discrimination, extends along the Atlantic border 

 of the United States — in some places far into the interior — and 

 appears besides in many isolated positions, covering an extent of 

 area probably not equalled in any other part of the world. 



Our tertiary and upper secondary have been successfully ex- 

 amined by Dr. Morton, Mr. Yanuxem, Mr. Conrad, Mr. Lea, 

 Mr. Nicollet, and others ; but this field is far from being ex- 

 hausted. 



It is worthy of remark, that the trifid tracks and impressions 

 on the new red sandstone of the valley of the Connecticut, so 

 zealously explored by Dr. James Dean of Greenfield, and both 

 explored, and figured and described by Prof. Hitchcock, leave 

 no reasonable doubt, that they are, at least in part, due to the feet 

 of birds* — some of them of colossal dimensions. It is certainly 

 possible, that among the impressions of this period, if not among 

 those already observed, may be found some of the batracians or 

 chirotheria of the strata of England and Germany. The doubts 

 concerning the latter having been cleared up by the discovery of 

 bones, by the aid of which Mr. Owen, the great comparative 

 anatomist of London, has ventured to restore the form of batra- 

 cian reptiles as large as a bull or an elephant, we may hope that 

 a fortunate development of the bones of these ancient birds may 



* Reptiles would seem more probable, but many of the tracks appear decidedly 

 those of birds. 



Vol. XLiii, No. 2.— July-Sept. 1842. 31 



