98 IOWA ACADEMY OP SCIENCES. 



the temperature must have been close to 20 degrees F. 

 Apparently tender vegetation — beautiful -wild flowers — seem 

 to laugh at these little touches of winter, and likewise, in the 

 Hot Springs where the water boiled eggs in twenty minutes, 

 at least one alga grows in considerable abundance. 



THE DISTRIBUTION OF LOESS FOSSILS. 



BY B. SHIMEK. 



It has perhaps been noted that the loess molluscs thus 

 far reported in the literature of the subject are, for the 

 most part, from localities in close proximity to larger streams. 

 This fact may have suggested the thought to those unfamiliar 

 with the modern habits and present distribution of these 

 molluscs that the adjacent streams had in some way something 

 to do with the entombing of the shells now found in the loess. 

 That the loess is most richly fossiliferous near streams is 

 generally, though not always, true. The abundance of fossils 

 is a decidedly variable quantity. There are exposures near 

 streams which exhibit fossils in profusion, and others which are 

 wholly barren. On the other hand, exposures quite remote 

 from streams contain fossils, — though in such situations a 

 proportionately much larger part of the loess is entirely devoid 

 of them. 



This fact has sometimes led geologists to attempt to dis- 

 tinguish, in varying degrees, between the loess adjacent 

 to streams and loess more remote. Whatsoever distinction 

 may be observed in the physical character of the loess of var- 

 ious deposits,"^ no distinction can be based on the presence 

 or absence of fossils alone. The simple fact that one deposit is 

 fossiliferous and another is not, does not prove, nor even 

 indicate, that the deposits were formed under wholly, or even 

 materially, different circumstances. In the one case there are 

 no fossils, simply because there were no shells to be buried; in 

 the other, fossils are common because shells were abundant on 

 the old land surfaces, where they were covered as other 

 imperishable objects would have been covered. 



*For one of the most recent discussions of the loess, with reference to its variation 

 according- to distance from streams, see Doctor Chamberlin's article in the Journal of 

 Geolot^y, Vol. V, No. 8, p. 795. 



