March 21, 1913] 



SCIENCE 



457 



five drift sheets exhibited in Wisconsin, as fol- 

 lows: First drift, a very old, thin drift; second 

 drift, a very old, thick drift correlated with the 

 Kansan of northeastern Iowa; third drift, a rela- 

 tively old, thin drift, correlated with the lowan 

 of northeastern Iowa; fourth drift, a relatively 

 thin, fresh drift, correlated with the early Wis- 

 consin of northeastern Illinois; fifth drift, the 

 Wisconsin drift. Extensive alluvial and lacustrine 

 deposits in old valleys and lowlands, of inter- 

 glacial origin between the second and third drifts. 

 The loess deposits are of later origin than the 

 third drift and older than the fourth. 

 The "Moraines" of Kansas: J. E. Todd. 



Certain bouldery hills have been designated as 

 glacial moraines by several writers on Kansas 

 geology. This paper discusses their locations and 

 relations to the former Kansan Ice sheet and 

 present lines and levels of drainage and shows 

 that they are not true moraines but river-laid 

 deposits. 

 Traces of an Early Wisconsin Flood: J. E. Todd. 



Attention is called to a deep silt which fills por- 

 tions of the valleys of the Missouri and Kansas 

 rivers in eastern Kansas, and which can not be 

 correlated with the loess, because of its lower 

 level. Because of evidences of the excavation of 

 the valley so filled during and after the Kansas 

 stage of the ice, it is argued that the date of the 

 deposition of the silt was coincident with the 

 recession of the Ea.rly Wisconsin Ice, or more 

 definitely after the formation of the Altamont, or 

 first marginal moraine. This lower loess or ter- 

 race silt is further provisionally correlated with 

 terraces along the Missouri further north and its 

 tributaries in western Iowa. 

 The Sangamon Interglacial Stage in Minnesota: 



Wareen Upham. 



Three chains of lakes on the till area of Martin 

 County, one of the central counties of the southern 

 tier in Minnesota, adjoining Iowa, are ascribed 

 to interglacial erosion of rivers flowing south, 

 where now the courses of drainage pass eastward. 

 The duration of this interglacial stage is esti- 

 mated by Winehell, from changes of the course of 

 the Mississippi Eiver in and near the Twin Cities 

 of Minneapolis and St. Paul, to have been about 

 15,000 years. It seems to be represented in the 

 history of the Quaternary lakes Bonneville and 

 Lahontan by the stage of their desiccation between 

 their previous prolonged stage of high water and 

 their ensuing higher but more brief rise of water; 

 and it is correlated with the Sangamon inter- 



glacial stage between the Illinoian and lowan 



stages of glaciation. Its time is estimated to have 



been approximately from 40,000 to 25,000 years 



ago. 



The delation of the Keewatin and Labrador Areas 



of Glaciation: Warren Upham. 



The Kansan and Illinoian drift sheets are re- 

 garded as mainly of contemporaneous age. They 

 were deposited respectively by the farthest south- 

 ward extensions of the Keewatin and Labrador 

 icefields. The belt of confluence of these icefields 

 extended from the borders of the drift northward 

 along or near the course of the Mississippi Eiver 

 up to the Wisconsin driftless area, which also 

 reaches short distances into Illinois, Iowa and 

 Minnesota. Beyond the driftless area, these Kee- 

 watin and Labrador currents of the continental 

 ice-sheet were confluent along a belt or line pass- 

 ing north-northwesterly through Minnesota to the 

 vicinity of Winnipeg, Manitoba and onward along 

 the axis of Lake Winnipeg. At St. Paul and 

 Minneapolis and northward, fluctuations of the 

 line of confluence during the Wisconsin stages of 

 glaciation produced extensive interbedding and 

 sometimes a confused mingling of the Keewatin 

 and Labrador drift formations. 

 Types of Iron Ore in Tennessee: C. H. Gordon. 



Bead by title. 

 Criteria for Distinguishing Various Sorts of Com- 

 mon Deposits (illustrated) : A. C. TROWBRmoE. 

 The Age of the Mesabi Iron-hearing BoeTcs of 



Minnesota: N. H. Winchell. 



This paper gives a very brief summary of for- 

 mer opinion, and presents new evidence which goes 

 to show that the Mesabi rocks are a part of the 

 great Keweenawan formation. 

 Angular Amphitheaters of the Grand Canyon: 



Charles E. Keyes. 



One of the most perfectly enigmatical features 

 concerning the physiognomy of the Grand Canyon, 

 in Arizona, and one to which little especial atten- 

 tion has been directed, is a certain regularity in 

 the notably serrated character of the walls. But- 

 tresses, reentrants and pyramids have a conspicu- 

 ously rectangular ground-plan. So pronounced is 

 this characteristic and so large is the scale that 

 it is even emphasized in the latest contour -maps 

 of the district. The angularities of the buttresses 

 and pyramids are readily explained by the double 

 system of master-joint structure. The deep re- 

 entrants or amphitheaters are not so easUy dis- 

 posed of, especially since all of the surface drain- 

 age, which is very deficient, of the general plateau 



