July 25, 1913] 



SCIENCE 



135 



logical Survey, it is evident that this 

 " gumho " corresponds to his " Loveland," 

 which he has found there well exposed and 

 widely distributed, and has been the first to 

 recognize. 



The Bowlder-tearing Portion of the Eansan 

 At the fine exposure at Coon Valley only a 

 trace of Kansan bowlder-bearing clay is left; 

 but it appears in all the deep cuts to the south. 

 The characteristics of this portion of the drift 

 have been so frequently stated that a descrip- 

 tion is here omitted. South of Whitebreast 

 Creek and across Lucas County numerous 

 sand bowlders form a conspicuous feature of 

 the Kansan bowlder clay. In places, where 

 " gumbo " is not present, there is evidence of 

 post-Kansan wash. 



No Aftonian nor Neiraslcan Exposed 

 The study of the section was undertaken 

 with the expectation that numerous exposures 

 of Aftonian interglacial deposits and of Ne- 

 braskan drift (sub- Aftonian) would be found ; 

 but the cuts are through the hills, and fills 

 extend across the valleys. At the Avon gravel 

 pit in the southern part of Polk County a 

 steam shovel is now removing a coarse sand 

 close to a level at which near by mastodon or 

 elephant remains are said to have been found 

 a number of years ago. These deposits are 

 thought to be of Aftonian age. In a cut in 

 Marion County the bottom of the Kansan 

 drift there exposed contained a bowlder of 

 blue clay apparently Nebraskan. With the 

 exception of these two places all evidence of 

 distinct Aftonian and of distinct Nebraskan 

 is wanting. (The work of excavation is not 

 fuUy completed near the southern part of 

 Marion County.) 



The Des Moines Formation 

 The Des Moines shales are frequently found 

 above the level of the track bed from the out- 

 crop near Coon Valley to the northern boun- 

 dary of Lucas County, south of which place 

 they appear but once. These exposures afford 

 excellent opportunity to study variations in a 

 preglaeial surface. 



The exposures in their present perfection 

 will not last long, but at present they will well 

 repay a day's tramp south from Des Moines, 

 or, at Chariton, north from Chariton River. 



Achnowledgments 

 During the summer several of the most im- 

 portant exposures were visited by Professors 

 George F. Kay, B. Shimek and James H. 

 Lees together with the writer, and the condi- 

 tions found discussed in the field; but the 

 parties named are not responsible in any way 

 for the above presentation. 



John L. Tilton 



TEE AMEEICAN ASSOCIATION OF 

 MUSEUMS 



The eighth annual meeting of the American 

 Association of Museums was held in Philadelphia, 

 June 3-5. The most prominent feature of the 

 eonvention was the discussion of general questions 

 of policy in relation to future work. 



The representation of museums of science in the 

 membership has always largely exceeded that of 

 museums of art, although the essential idea in the 

 organization of the association was to afford a 

 common meeting ground for the discussion of the 

 ' ' principles of organization and administration of 

 museums, and their problems of technique, rather 

 than matters of art, history or science as such." 

 There is a strong sentiment among both science 

 and art members that, since all museums exist for 

 the purpose of giving visual expression to ideas, 

 the methods of accomplishing this purpose must be 

 fundamentally similar and vary only in applica- 

 tion according to the nature of the material and 

 of the ideas to be expressed. The field of the 

 association, therefore, in no way conflicts with any 

 of the many scientific, artistic or historical socie- 

 ties. For the purpose of promoting a more gen- 

 eral appreciation of these facts, and to endeavor 

 to secure greater equality of representation of the 

 various classes of museums in the membership and 

 in the programs of the meetings, a special com- 

 mittee was appointed. With an art man as presi- 

 dent for the ensuing year, the time seems par- 

 ticularly opportune for this movement which is so 

 essential to the full function of the association. 



A committee was also appointed to consider 

 what methods the association may adopt to pro- 

 mote the increase and successful development of 



