82 REPOKT OF THE SECKETARY. 



South Atlantic Division. 



Appalachian District. — At the time of the withdrawal of Mr. G, K. 

 Gilbert from the District of the Great Basin, he had in course of prepara- 

 tion an elaborate memoir, embodying the results of his investigations 

 concerning the ancient Lake Bonneville and its boundaries, while his 

 immediate assistant, Mr. Eussell, was engaged in the preparation of a 

 like report upon Lake Lahontan and a paper upon the Mono Basin. For 

 these many illustratious had been made, and others that were being 

 drawn required constant supervision. Attention to this material occu- 

 pied much of Mr. Gilbert's time, but early in the Held season he found 

 opportunity to make a preliminary study of the structure of the Appa- 

 lachian system. For this purjjose he proceeded, via Lynchburg, Va., 

 to Asheville, N. C. From this point a series of excursions were made to 

 Mount Mitchell, Eoan Mountain, and to the valleys of several of the 

 tributaries of the French Broad. The journey was then continued south- 

 ward across Tennessee, and as far into Georgia as Ellijay. While the 

 object of this trip was the general study of the history of the Appala- 

 chian system, especial attention was given to that phase of it which is 

 represented by the ancient base-levels in the mountain valleys. Later 

 in the season Mr. Gilbert made similar observations upon the terraces 

 of the valleys of the Passumpsic, Connecticut, and Mohawk, for com- 

 parative purposes. In the mean time, he sent the assistant geologists, 

 who had previously acted in this region under the Director's immediate 

 instructions, but who were now placed under his direction, to make a 

 detailed study of the geologic phenomena of the Kanawha Valley, West 

 Virginia, of the country in the vicinity of the White Sulphur Springs, 

 and of a portion of the great valley of eastern Tennessee. At the close 

 of the calendar year satisfactory progress was reported in these several 



fields of work. 



Division of the North Mississippi. 



Glacial District. — A summary of what was accomplished by Prof. T. 

 C. Chamberlin and his assistants shows six months' of oflice duty in 

 connection with the i>revious season's material and six months of out- 

 door work in extending the research into new fields. The first half of 

 the year was .given to the preparation of a paper on " Requisite and 

 Qualifying Conditions of Artesian Wells," for the Director's Fifth An- 

 nual Report, a report upon gravel deposits, and the collation of the ob- 

 servations made upon glacial striation. The field work of the last half 

 of the year included (1) an expansion of the previous studies of the drilt- 

 less area of Wisconsin, Illinois, Iowa, and Minnesota ; (2) the continua- 

 tion of previous work in Dakota, more particularly the detailed study 

 of the moraines of the southern part, and a critical examination of their 

 relation to other deposits ; (3) the tracing of the outer limit of the north- 

 ern drift from the point to which it had been previously traced in Indi- 

 ana westward to the Mississippi River ; (4) the study of the terraces ot 



