February 20, 1903.] 



SCIENCE. 



293 



ties along the Rocky Mountain front south- 

 ward into New Mexico and eastward into 

 Oklahoma. The shales contain fossils, by 

 which they can be correlated with the 

 Lower Cretaceous of Texas. 



A characteristic Lower Cretaceous fossil 

 from these beds was exhibited. Professors 

 Scott and Williston, in discussion, consid- 

 ered that the Lower Cretaceous age of the 

 beds was proved by the vertebrate fossils. 

 Both preferred the term 'Como beds' to 

 Atlantosaurus beds. Mr. Darton had dis- 

 covered similar Lower Cretaceous inverte- 

 brates in these beds. 



Mr. Stanton argued that the occurrence 

 of lithologically similar beds on the Red 

 beds was not conclusive evidence of their 

 stratic equivalency. 



The Cretaceous-Eocene Boundary in the 



Atlantic Coastal Plain: W. B. Clabk, 



Baltimore, Md. 



Some of the difficulties encountered in 

 cartographically representing the bound- 

 ary line between the Cretaceous and Eocene 

 deposits along the Atlantic coastal border 

 were presented. These difficulties consist, 

 in New Jersey, in locating, on account of 

 the continuity of deposition, a clearly de- 

 fined line separating the Eocene from the 

 Cretaceous; and in Delaware and Mary- 

 land, in determining the boundary line, 

 because of the apparent mechanical trans- 

 portation of Cretaceous fossils into the 

 Eocene deposits where they exist side by 

 side with Eocene forms. 



The formations discussed are: (1) 

 Potomac, possibly Upper Jurassic to Lower 

 Cretacic, (2) Upper Cretacie, (3) Eocene, 

 (4) Miocene and Pleocene. Marked differ- 

 ential movements occurred at different 

 periods accompanied by pronounced trans- 

 gressions and retrogressions. In discus- 

 sion Bailey Willis made a comparison be- 

 tween the Atlantic and Pacific coast belts. 



The Marl-loess of the Lower Wabash Val- 

 ley: M. L. Fuller, "Washington, D. C, 

 and F. G. Clapp, Boston, Mass. 

 A study of the marl of the lower por- 

 tion of the valley of the Wabash River in 

 southern Indiana and Illinois shows it to be 

 the equivalent of the loess, i-eplacing the 

 latter over considerable ai-eas. This marl- 

 loess is usually a little coarser than the 

 common loess and carries about 30 per cent, 

 of CaCOa, as compared with less than 5 

 per cent, in the common type. Numerous 

 exposures have been discovered in which 

 the materials are distinctly or even con- 

 spicuously stratified, and in some instances 

 thin interbedded layers of fine gravel were 

 noted. It is frequently abundantly fos- 

 siliferous, the forms being stated as a mix- 

 ture of aquatic and land species. The strati- 

 fied marl-loess appears to reach an altitude 

 of about 500 feet, or some 120 feet above 

 the flood plain of the river. Instead of 

 forming a mantle conforming to the sur- 

 face inequalities, as is the case with the 

 common loess, the marl-loess frequently oc- 

 curs as extensive flats on broad gently slop- 

 ing terraces at elevations ranging from 40 

 to 120 feet above the river! Beneath these 

 there is usually buried a somewhat rugged 

 topography. In distribution, the marl- 

 loess is confined mainly to the east side of 

 the valley, an occurrence which is most 

 favorable to the hypothesis of wind origin, 

 but the balance of evidence appears to be in 

 favor of the view, with certain limitations, 

 of aqueous origin. 



The paper was illustrated by lantern 

 slides. Professor Chamberlin stated that 

 the stratified deposits in question had per- 

 haps been wrongly called loess by himself 

 and others, as they were not like the true 

 loess. He suggested that the term, loess- 

 like alluvium, was more expressive of its 

 character. The paper was also discussed 

 by Professor Salisbury and others. 



