September 30, 1921] 



SCIENCE 



307 



Academy on "America as a world power." Fol- 

 lowing the address President and Mrs. Hillman of 

 Simpson held a reception for the visitors. 



On Saturday morning the sections concluded the 

 reading of papers and the Iowa sections of the 

 American Chemical Society and the Mathematical 

 Association of America held their meetings. At 

 the business meeting the constitution was revised 

 to drop the classes of corresponding fellow and 

 corresponding associate. Members are to be classed 

 as honorary fellows, life fellows, fellows and asso- 

 ciates. Six sections of the Academy are provided 

 for and the chairmen of these, with the elected 

 officers, constitute the executive committee. An 

 editorial committee is provided for to assist the 

 secretary in preparing manuscripts for publication. 

 Officers were elected as follows: President, D. "W. 

 Morehouse, Drake University, Des Moines; Vioe- 

 President, E. B. Wylie, State University, Iowa 

 City; Secretary, James H. Lees, Iowa Geological 

 Survey, Des Moines; Treasurer, A. O. Thomas, 

 State University; Presidents of Sections: Botany, 

 E. B. Wylie; Zoology, Harry M. Kelly, Cornell 

 College, Mount Vernon; Geology, A. G. Trowbridge, 

 State University; Physics, L. P. Sieg, State Uni- 

 versity; Chemistry, P. A. Bond, State University; 

 Mailiematics, W. J. Eusk, Grinnell College, Grin- 

 nell. 



The following program was presented: 



CHEMISTKT 



Further work in the study of free energy of 

 aqueous solutions: J. N. Pearcb and H. B. Hart. 



The effect of relative positions of the hydroxide 

 and amino radicals in the migration of acyl from 

 nitrogen and oxygen: L. Charles Eaipobd and H. 

 A. Iddles. 



A chemical study of dolomites: Nicholas 

 Knight. 



Twenty-seven specimens were included in the 

 investigation. They belonged to different parts of 

 the United States and to a number of foreign 

 countries. It was found that the term dolomite 

 is rather loosely used, as the specimens ranged all 

 the way from fairly typical dolomites to ordinary 

 limestones. Indeed, some of the specimens proved 

 to be quite pure sandstones. 



A brief review of the various methods of pro- 

 ducing dolomite artificially was included in the 

 paper. 



GEOLOGY 



Three glacial tills at Ames, Iowa: John E. 

 Smith. This illustrated paper treats of the char- 



acter of these deposits and of their relations to 

 each other. The observations were made in a 

 large excavation opened to receive the foundation 

 of Wesley Hall just south of the grounds of Iowa 

 State College on Lincoln highway. At this place 

 most of the Wisconsin till had been removed by 

 erosion prior to the beginning of this work. A 

 zone of red soil separates it near the top of the 

 pit from the Kansan below. Beneath the Kansan 

 which covers a rough, eroded surface, is a third 

 till believed to be the Sub-Aftonian or Nebraskan. 



Molian deposits in Webster county, Iowa: John 

 E. Smith. The location, distribution and origin 

 of a deposit which overlies the Wisconsin till in 

 this area is discussed in the paper. A typical 

 section shows one foot or more of each of the 

 following which are named in order of their occur- 

 rence from the surface downward: Section: (1) 

 Clay, gray, with no pebbles. (2) Soil, a black 

 zone of humus with few pebbles. (3) Subsoil, 

 brown, with glacial pebbles. (4) Glacial till, un- 

 weathered. The principal question involved con- 

 cerns the origin of number 1 of the section, which 

 one authority holds to be free from glacial pebbles 

 because of a postulated advanced stage of weath- 

 ering. 



The existing stage of erosion in the United 

 States: Arthue C. Trowbridge. Inspection of 

 398 topographic maps published by the U. S. Geo- 

 logical Survey since 1912, and representing 41 of 

 the states of the Union, reveals no illustration of 

 any considerable area of surface which has been 

 reduced to old age of a cycle of erosion by the 

 work of streams. Old valleys are fairly abundant 

 but no general surface is found which can be said 

 to have been baseleveled or even peneplained. This 

 is interpreted to mean that the present time was 

 so closely preceded by uplift and enlargement of 

 land that there has not since been time for streams 

 to reduce the surface beyond maturity, or at best, 

 beyond early old age. Either the Pleistocene per- 

 iod was too short to permit land uplifted in the 

 latest Tertiary to be greatly reduced — an explana- 

 tion which seems unlikely to the writer — or there 

 has been Pleistocene or post-Pleistocene uplift. 



Some north-south topographic profiles in tlie 

 United States: Aethur C. Trowbridge and John 

 T. Lonsdale. That part of the surface of North 

 America which was not covered by the Pleistocene 

 ice sheets was, during the glacial period, subject 

 to the ordinary processes by which land ia de- 



