REPORT OF THE SECRETARY. 75 



line of division between the Laramie group and the beds that lie beneath 

 it. Collections were made at various points, mainly of fossils from 

 strata' of the Laramie group, and the numerous coal outcrops in the 

 vicinity of the railroad were examined, as were also the borings for 

 artesian wells at Bismarck in Dakota, and at Billings in Montana. 



Quaternary geology. — An investigation of the glacial and associated 

 formations of the interior basin has been in progress under charge of 

 Prof. T. G. Chamberlin. In the early part of June he made a brief re- 

 examination of the stony clays bordering Lake Michigan, with a view 

 to discriminations between true glacial deposits and those produced by 

 floating ice. Later in the month he made a cursory examination of 

 some points on the southern border of the newer drift in Central Iowa, 

 and on the loess and drift of Northeastern Nebraska, carrying a recon- 

 naissance as far west as Fort Niobrara. In July he studied the outer 

 bonier of the drift in Dakota, adjacent to and west of the Missouri 

 River. In August a reconnaissance of the drift margin in the Ohio 

 Basin in Southern Illinois, Indiana, and Southwestern Ohio was under. 

 taken. September and the remainder of the available field season, 

 reaching into the early part of December, were devoted to a supple- 

 mentary examination of the bqrder of the later drift and of its moraines 

 in the plaine region, stretching from the Scioto to the Illinois Valley, in 

 which the ridging of the drift is least conspicuous. 



Prof. J. E. Todd, as assistant, devoted the main portion of the field 

 season to an investigation of the moraines and associated drift deposits 

 of the Territory lying between the James and Missouri Valleys and 

 south of the Northern Pacific Pail way in Dakota. Subordinately he 

 made brief supplementary studies of the glacial phenomena of the south- 

 eastern corner of Dakota and the northeastern border of Nebraska. 



The chief subject assigned Prof. R. D. Salisbury, assistant, was the 

 character, quantity, and topographical associations of the residuary 

 clays and other disintegration products of the driftless region of Wis- 

 consin, Minnesota, Iowa, and Illinois. In connection with this study 

 he traced out the limits of some portions of the driftless area that had 

 not been determined with accuracy, and examined the character of the 

 drift border with a view to comparison with the observations on the 

 outer drift margin above indicated. He also gave attention to the loess- 

 like loams of the western and southern portions of the district and to 

 the valley drift. In November he was temporarily diverted from these 

 studies to assist in glacial examinations in the Wabash Valley. In the 

 latter part of November he transferred his field to Eastern Missouri, and 

 began an investigation of the residuary clays, loess, and drift border 

 analogous to that previously undertaken in the driftless region, and 

 with the object, among others, of intercomparison. This work was con- 

 tinued until interrupted by snow-fall, about the middle of December. 



The surface geology of the District of Columbia. — The superficial de- 

 posits of Washington, D. C, and vicinity have been made the subject 



