20 AWNUAL REPORT OF THE 



student in Geology S20c, spent ten weeks tracing out the upper 

 marine limit of the so-called Champlain sea from Cape Ann along 

 the coast of New Hampshire and Maine to and beyond Portland, 

 with the result that the extent of the submergence appears now 

 to be satisfactorily determined. 



Professor Raymond gave Palaeontology 1, 2, and 20. Three 

 papers were published by students as a result of work done in 

 Palaeontology 20: — by R. M. Field. 1. The use of the Roentgen 

 ray in palaeontology. Amer. journ. sci., May, 1915, ser. 4, 39, 

 p. 543-550, pi. 8. 2. On the validity of the genus Plethopeltis. 

 Ottawa naturalist, July, 1915, 29, p. 37-43; by E. W. Shuler. 

 3. A new Ordovician eurypterid. Amer. journ. sci., May, 1915, 

 ser. 4, 39, p. 551-554, f. 1-6. Mr. Shuler devoted the greater 

 part of his time in Palaeontology 20 to his thesis The geology of the 

 Walker Mountain overthrust block. 



An unexpended balance of the grant from the Shaler Memorial 

 Fund allotted in the previous year enabled Professor Raymond to 

 spend two weeks in Pennsylvania in the study of certain sections 

 whose interpretation had a direct bearing upon the problems of the 

 correlation of the eastern American with the northern European 

 Ordovicians. During this trip he was accompanied by Mr. R. M. 

 Field, and for a part of the time, by Mr. E. W. Shuler. In May, 

 Professor Raymond, accompanied by the same graduate students, 

 spent a week in studying certain problems in the stratigraphy of 

 the Ordovician of the Mohawk Valley of New York. 



The student collection has received during the year, by donation : 

 Cambrian and Tertiary fossils from Mr. W. G. Foye; by purchase: 

 about fifty specimens of Upper Cambrian fossils from Minnesota 

 and Wisconsin, about 500 specimens of rocks and fossils from south- 

 western Virginia, and five plaster models of fossils. 



In Economic Geology, Professor Graton gave the following 

 courses: Geology 10, Geology 18 in part, and Geology 20b. Two 

 changes from previous years may be noted in connection with 

 these courses: (a) In Geology 10, laboratory work was offered 

 for the first time and was pursued by about half the class. The 

 experiment proved so satisfactory that laboratory work is now 

 required, (b) As a part of Geology 18, non-metalliferous economic 

 geology, Dr. Ralph Arnold gave the series of ten lectures on the 

 Geology of petroleum, already noted. The attendance at these 

 lectures, ranging from 38 to 65, about half of them Harvard men, 

 contrasted strongly with the small number of students registering 

 each year in the regular work of Geology 18, and indicates how 



