Mat 21, 1920] 



SCIENCE 



521 



sodes of deformation, one before and one after the 

 laying down of these beds. The conglomerates are 

 tentatively correlated with the Fort Union, as that 

 formation is described by Hewett and Lupton in 

 recent papers. These workers also recognize two 

 episodes of disturbance, quite probably the same 

 two noted by the writer. One they place as post- 

 Lance and pre-Fort Union, the other as post-Fort 

 Union and pre-Wasatch. If their correlations are 

 correct they find both episodes of diastrophism to 

 be post-Lance. This appears to be contrary to the 

 idea of Knowlton and others who point very defi- 

 nitely to a pre-Lance (pre-Arapahoe) period of 

 folding. We must conclude, therefore, either that 

 the so-called Lance and Fort Union of the Big 

 Horn Basin, as the terms are used by Hewett and 

 Lupton, are not the equivalents of the Lance and 

 Fort Union described by Knowlton, or else we 

 must conclude that there are three episodes in the 

 orogeny of the Eocky Mountains, one pre-Lance 

 and two post-Lance. 



The present status of the Pleistocene in Illinois: 

 MoERis M. Leightoij. Detailed studies on the 

 Pleistocene in Illinois, begun in 1886 under the 

 supervision of Professor T. 0. Chamberlin, led to 

 the publication in 1899 of Monograph XXXVIII. 

 on "The Illinois Glacial Lobe," by Mr. Frank 

 Leverett. Aside from certain obscure problems 

 which were left for further study, two important 

 questions have since arisen from changes and shifts 

 in the classification of American drift-sheets. 

 When the verity of the lowan epoch was questioned, 

 subsequent to the publication of Monograph 

 XXXVIII. the lowan drift in Illinois was dis- 

 carded. Since then, the area has been referred to 

 the lUinoian stage, then to a substage of the 

 lUinoian, and still more recently a considerable 

 portion has been suggested as being possibly Early 

 Wisconsin. Whether the drift in northwestern Illi- 

 nois is wholly or in part Illinoian, lowan or Early 

 Wisconsin remains to be determined by critical 

 and comparative field-work. The Wisconsin drift 

 deposits were divided into two major drifts in 

 Monograph XXXVIII. but later were reduced to 

 two subordinate stages, and more recently a sus- 

 pension of the sub-stages "Earlier" and "Later" 

 has been proposed. An early critical study of the 

 drift of northwestern Illinois and of the basis of 

 classification of the Wisconsin drift-sheets is con- 

 templated. 



A possible factor in the origin of dolomite: W. 

 A. Taer. It is believed from the study of the areal 

 and time distribution of dolomite that its origin 



is directly dejiendent upon shallow continental 

 seas, or lakes, for the necessary concentration of 

 magnesium salts in suflScient amounts for its for- 

 mation; that the deposition took place upon the 

 sea or lake bottom; that in such seas or lakes we 

 have an adequate source of magnesium; and that 

 such a mode of origin is compatible with the inter- 

 bedding of dolomite with limestone. 



Some glacier studies in Alaska: Eollin T. 

 Chamberlin. The ultimate purpose of these 

 studies was to obtain a better understanding of 

 the true nature of glacier motion. Some of the 

 more immediate purposes were to demonstrate 

 movement along definite shear planes which would 

 indicate brittleness and rigidity of materials; and 

 also to determine what relation there might be 

 between the rate of shearing and the temperature, 

 time of day, daily range of temperature, amount 

 of water entering the ice, and variable meteorolog- 

 ical conditions. This investigation was under- 

 taken by means of a self-recording clock-work 

 apparatus which was attached to two rods driven 

 into the ice, one above the fracture plane to be 

 investigated and the other 'below it. The appa- 

 ratus was sensitive to shearing amounting to as 

 little as one hundredth of an inch. Many difi- 

 eulties were encountered and only indifferent suc- 

 cess achieved. Such records as were obtained 

 seemed to indicate that shearing was more rapid 

 between 6 p.m. and midnight than between 6 a.m. 

 and noon. This would not be at the time of great- 

 est melting but lagging after it. It would be 

 when there was the most water in the ice. A study 

 of the "sloughing off" of Child's Glacier and 

 especially the relation between the shearing planes' 

 and the blue bands constituted an important and 

 critical part of the investigation. 



The stratigraphy of the Chester series of south- 

 ern Indiana: Clyde A. Malott and J. D. Thomp- 

 son, Jr. The following is the first attempt to give 

 the entire detailed stratigraphy of the Chester 

 Series of Indiana, using the names adopted by the 

 Kentucky and Illinois surveys and by the writer 

 in a former publication: 



Buffalo Wallow Siberia Is. at base, 1-12 feet; 

 Formation overlaid by some 60 feet of 



sandy sh. and a thin Is. 

 Tar Springs Massive ss., 0-75 feet, and sh.. 



Formation 50-125 feet; thin impure 



limestones in shale when sa. 

 is a;bsent or thin. 

 Glen Dean Massive, often oolitic lime- 



Limestone stone; 10-45 feet. 



