REPORT OF THE SECRETARY. 71 



to problems whose solutiou promises to have important eeonomic value. 

 After making a preliminary inquiry into the geology of the Cobscook 

 Bay district, he began a study of the district adjacent to I^Tarragansett 

 Bay, the coal-fields of which he compares in character with those of 

 Pennsylvania, and hopes to see rendered commercially important. An- 

 other inquiry to which he has given attention is the amount of salt- 

 water marshes on the eastern coast of the United States, the extent to 

 wdiich these arc reclaimed, and the most feasible means of bringing 

 them into tillable condition. The experience of other countries ho 

 found to be of such a character as to justify the hope that at least 

 20,000 square miles, and possibly twice that area, may be easily won to 

 agriculture. Professor Shaler publishes a report on the " Salt Marshes 

 of the United States " in the Sixth Annual Report of the Director of 

 the Survey, and a report on the "Geology of Martha's Vineyard" in 

 the seventh. 



Appalachian Division of Geology. — Mr. G. K. Gilbert continued, with 

 a corps of assistants, the investigation of the geology of the Appala 

 chiau i\[ountaius in the States of Maryland, Virginia, West Virginia, 

 Kentucky, Tennessee, North Carolina, Georgia, and Alabama. In the 

 systematic conduct of this work he proposes to survey and measure 

 with great care four sections, crossing the belt at right angles. The 

 rocks to be studied being much disturbed, a simple linear section does 

 not aiford a sufficient guarantee of accuracy', and he substitutes for it 

 the complete structural survey- of a strip of country 20 miles broad. 

 When this is finished it is believed that the structure of the entire belt 

 can be unraveled with comparative ease and rapidity. Of Mr. Gilbert's 

 assistants, Mr. Bailey Willis was engaged on the French Broad section, 

 Mr. I. C. Russell on the Alabama section, Mr. H. R. Geiger on the Po- 

 tomac section, and Prof. I. C. White made an investigation of the strati- 

 graphy of the coal-measures in the valley of the Great Kanawha. The 

 geologic literature of the Aiipalachian district being very copious, and 

 Mr. Gilbert being unwilling to pass bj' without acknowledgment the 

 work of his ijredecessors, a subject bibliographj' of this literature has 

 been undertaken, and 0,000 bibliographic cards have been prepared, 

 which contain each a reference to the jmges in a specific volume in which 

 any jjarticular subject is treated. The memoirs relative to the investiga- 

 tion of the " Quaternary History of the Great Basin" are in substan- 

 tially the same condition as last reported. 



Lalie Superior Division of Geology. — In this division Prof. R. D. Ir- 

 ving is engaged in a general investigation of those formations of the 

 jSTorthwestern States which underlie the basal fossiliferous or Potsdam 

 sandstone of the Mississippi Valley. A large portion of the field work 

 of Mr. Irving's assistants was spent in replacing the collections which 

 they were so unfortunate as to lose by the fire that occurred in the 

 science building of the University of Wisconsin in December, 1884. In 



