Deckmbee 4, 1896.] 



SCIENCE. 



813 



none of these colored drawings does justice 

 to the natural scenery. 



On the Atlantic coast the same combina- 

 tion of colors, although less brilliant, may 

 be seen in the Potomac outcrops in Mary- 

 land, now proved by vertebrate fossils to be 

 likewise Jurassic. Further north the reds 

 predominate in this horizon across Dela- 

 ware and Pennsylvania, but in the plastic 

 clays of New Jersey the strong, distinct 

 colors, usually in horizontal bands, are 

 dominant. On Staten Island and at various 

 outcrops along the northern shore of Long 

 Island, as well as on Block Island, the same 

 horizon is distinctly mai'ked by variegated 

 patches, while still further east, at Gay 

 Head, on Martha's Vineyard, the most 

 startling color display of the whole Atlan- 

 tic coast forms a flaming beacon that mari- 

 ners and geologists alike have for a century 

 held in high esteem. I know of no other 

 horizon of equal extent so readily distin- 

 guished from all others by its physical 

 features. 



EARLY INVESTIGATIONS. 



In the early days of American geology 

 the pioneers here, as in other branches of 

 science, attempted to refer everything to 

 European standards. In this way, strata 

 of various ages, as we now know, were 

 called by European names and were sup- 

 posed to represent equivalents. In this 

 general way, the terms Lias, Oolite, etc., 

 were applied to strata on the Atlantic coast. 

 It was soon found, however, by the actual 

 workers in the field, that our geological 

 sequence had only a general correspondence 

 with that of Europe or of other parts of the 

 world, yet some geologists still endeavor to 

 harmonize the time tables, but with only 

 moderate success. It is, however, now be- 

 coming known that this continent had its 

 own law of development, and that its fauna 

 and flora must be studied by themselves to 

 disclose their full significance. The time 



ratios of America certainly do not coincide 

 with those of Europe. The long periods 

 of Mesozoic time represented in Europe by 

 great deposition of many series of strata 

 were marked here by other means as well. 

 The rich fauna and flora that then lived 

 here do not have their exact counterparts 

 elsewhere. 



The apparent absence on the Atlantic 

 coast of the Jurassic as known in Europe 

 naturally led the early geologists to seek 

 its equivalent strata. The first supposed 

 identification seems to have been recorded 

 by W. B. Eogers, who called the eastern 

 Virginia coal beds Oolitic* These beds 

 are now regarded as Triassic. 



This eminent geologist also referred to 

 the Jurassic certain silicious, argillaceous, 

 and pebbly beds in Virginia and further 

 north, as possibly ' a passage-group anal- 

 ogous to the "Weal den of British geology. 'f 

 P. T. Tyson in 1860 referred the Maryland 

 clays to the Cretaceous, and later to the 

 Jurassic. I 



Long before this, in 1835, H. D. Eogers, 

 in his sketch of the geology of North 

 America, clearly recognized what is here 

 regarded as Jurassic as pertaining to one 

 great formation. He described this as ex- 

 tending along the tide-water plain of the 

 j!^.tlantic, from the Carolinas through Vir- 

 ginia, Maryland, Delaware, Pennsylvania, 

 and New Jersey, and also as continuing on 

 through Long Island to Martha's Vineyard 

 and Nantucket. He gave it the name of 

 'Ancient Alluvium,' but included in it the 

 plastic clay formation and part of the Gay 

 Head deposits, the latter of which he con- 

 sidered Cretaceous. § 



* Transactions Association American Geologists 

 and Naturalists, Vol. I., p. 300, 1843. 



t Proceedings Boston Society, Vol. XVIII., pp. 

 104, 105, 1875. 



% 1st Eeport State Chemist, Maryland, p. 41, 1860; 

 2d Eeport, p. 54, 1862. 



§ Report British Association, Edinburgh Meeting, 

 pp. 1-66, 1835. 



