474 REVIEWS 



its peculiar youthful typography, accidented by remarkable granite 

 bowlders, set superficially, embraced all the upper drift down to the 

 "Forest Bed," in other words all of "the Upper Till" of McGee's 

 classical paper on the drift of northeastern Iowa. As this upper till of 

 McGee was the type of the East lowan (Geikie's Great Ice Age, 760-62), 

 the name naturally followed the new interpretation. The youthfulness 

 of the surface and the freshness of the bowlders of this uppermost formation 

 seemed to force its separation from the well-eroded deeply-weathered sheet 

 which overlies the Aftonian beds at their typical locality. It has since 

 been found, however, that the fresher features of the lowan belong only 

 to a thin superficial formation, and it will probably now be agreed by most 

 experienced workers familiar with the region that the main part of McGee's 

 upper till is to be correlated with the super-Aftonian till at the typical 

 locality, thus restoring, in large measure, the original applicability of the 

 term. 



This sketch, even in its ^completeness, may serve to give a measure 

 of historic insight into the embarrassments that attend the correlation and 

 nomenclature of the American middle drift. 



Respecting the newer divergencies of opinion implied in Mr. Leverett's 

 paper, which involve the suggested dismissal of the lowan altogether, as a 

 distinct formation, or else its grouping under the lUinoian, it is appropriate 

 here to urge restraint, patience, and equipoise, for the distinguishing 

 phenomena, while pronounced and peculiar, are subtle in their gradations 

 and singularly puzzling. 



T. C. C. 



The Middle Devonian of Ohio. By Clinton R. Stauffer. Geo- 

 logical Survey of Ohio, 4th Ser., Bulletin No. 10. Pp. viii + 204, 

 17 plates. Columbus (1909), 1910. 

 The first chapter of this bulletin is devoted to a "General Discussion 

 of the Middle Devonian," which is considered under three headings. The 

 first part is a "Historical Sketch" in which the literature of the Middle 

 Devonian formations is carefully and fully reviewed. This is followed by 

 a consideration of "The Middle Devonian in Adjoining Territory," in 

 which the greatest amount of space is given to the equivalent formations 

 of Indiana and Michigan, which have also been studied by the author in 

 the field. In the closing part of the chapter is a "General Description of 

 the Middle Devonian" formations, which in Ohio are the Columbus and 

 Delaware hmestones and the Olentangy shale. The Middle Devonian 



