568 TRANS. OP THE ACAD. OP SCIENCE. 



of Mastodon were found in a bed of "local drift " near Alton, under- 

 lying the Loess in situ above, and also, in the same horizon, stone axes 

 and flint spear-heads, "indicating,"' says Mr. Worthen, " that the human 

 race was cotemporary with the extinct mammalia of the Quaternary 

 period." (P. 38.) This "local drift" is not particularly defined, fur- 

 ther than that it was older than the Loess. The fact would seem to show 

 that Man inhabited the uplands together with the Mastodon, iu the 

 earlier part of the epoch in which the Loess was deposited out of these 

 fresh-water rivers. The Loess itself is nothing but an altered drift, and 

 differs from any other fresh-water altered drift, not so much in containing 

 fresh-water and land shells, as in some difference in the character, 

 arrangement and appearance of the materials. 



Mr. Worthen further states that the mounds of the American Bottom, 

 " when carefully examined, are found to consist of drift clay and loess, 

 remaining in situ, just as they appear along the river bluffs, where 

 similar mounds have been formed in the same way by the removal of the 

 surrounding strata by currents of water"; and he observes that he had 

 found the Big Mound of St. Louis " to consist of about fifteen feet of 

 common chocolate brown drift clay at the base, which was overlaid by 

 thirty feet or more of the ash-colored marly sands of the Loess, the line 

 of separation between the two deposits remaining as distinct and well- 

 defined as they usually are in good artificial sections in the railroad cuts 

 through these deposits." (P. 34.) 



It is evident that this observation was made since the region around the 

 mound proper was graded down to the present level of the streets, and to 

 about that depth below the real base of the original mound ; but I know, 

 as many others do, from observations made while the process of grading 

 was going on, and before, that what Mr. Worthen has taken to be a line 

 of separation between the upper and basal portions of his mound, is only 

 the line that marks the bottom of the original mound where it stood upon 

 the natural surface of the ground ; and the ideu that the basal portion 

 was composed of the drift clay, and the top part of loess, is so far a 

 mere illusion. It is nevertheless true that the ground on which the mound 

 itself stands was this same chocolate brown drift clay, containing no 

 shells. This brown clay or loam is thus identified by Mr. Worthen as a 

 part of his " Drift proper,'' and so is by him taken out of Prof. Swallow's 

 Loess. Neither does the mound proper contain any fresh-water or land 

 shells. It is composed of a confused mass of ash-colored sandy loam of 

 various shades, having an appearance very much like the Loess. It is 

 very possible that it may be a knoll of loess left standing there on a 

 ground of the marine drift brown clay or loam ; and if the characteristic 

 fossils of the Loess were found in it, it might certainly be declared to be 

 a remnant of the Loess. No such fossils have been found in it ; but I 

 have found embedded in it a fragment of pottery, which is now in the 

 Museum of the Academy. (See Trans. Acad, of Sci. of St. Louis, vol. I., 

 p. 700.) 



This pottery may furnish eome evidence that the mound is artificial, 

 though not conclusive. If the mound be natural loess, then the pottery 

 would furnish another proof that Man existed here in the age of the 

 Mastodon and the Loess deposit ; but if it be artificial, the pottery may 

 have been carried into the mound with the materials of which it was con- 

 structed, at a much later date. 



In the "Geological Survey of Missouri" (p. 72), some analyses of 

 the Mississippi Loess are compared with those of the Loess of the Rhine, 

 and among them an analysis of one specimen from the Big Mound of St. 

 Louis, which corresponds very nearly with those of specimens from 

 other localities of the Loess, and all of them are said to show " a striking 

 coincidence'' in composition with the European Loess. But considering 

 that the materials of the Loess were chiefly derived from the finer mate- 

 rials of the marine drift clay and loam, no great difference should bo 

 expected, pei haps, in these analyses; and as the mound would be com- 



