2l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 93 



Dr. A. L. Lugn, of the Geology Department of the University of 

 Nebraska, who made a careful geologic examination of the deposits. 

 The middle valley of the creek, i. e.. Bird Creek Canyon, has been 

 filled by many feet of loess washed in from above, and it is through 

 this fill that it has cut down to its present bed. The gully walls in this 

 section range from 5 to 30 feet in height but probably average about 

 15 feet in the canyon proper. Just above the point investigated by us 

 the creek swings to the south against an outcrop of Dakota sandstone, 

 then swings north and west out into the center of the narrow canyon. 

 Here at a bend in the creek occur the covered gravel beds which are 

 exposed on both sides of the stream. The best exposure is on the 

 south bank, which is nearly vertical. A cross-section of the south bank 

 at this place showed the following descending strata : 



1. Dark organic soil, i foot (approximately). 



2. Yellow washed-in loess, 1 1 feet. 



,1. Thin stratum of blue clay (perhaps an old soil layer), 6-12 inches. 



4. Stratum of gravel, pebbles, and shale, 3 feet (containing bones and artifacts). 



5. Blue and yellow clay, from this point down as far as was dug. 



6. Total height of bank at this point, 16 feet (average). 



Underlying the above deposits at varying depths are horizontal beds 

 of Pennsylvanian limestone. 



Excavations in stratum 4 were conducted by smoothing off a sec- 

 tion of the gully wall (pi. 22, fig. 2, a) and troweling out the gravel, 

 etc., for a depth of a foot or so back into the bank. This layer is 

 composed of small rounded pebbles and gravel with small pockets of 

 blue shale. The gravel contained numerous fragments and chips of 

 ferruginous flint (pi. 22, fig. 2, c, f, k), nodules of flint with a 

 limestone matrix (pi. 22, fig. 2, b, d), crude and broken retouched 

 artifacts (pi. 22, fig. 2, c, i, j), and fragments of fossilized bone 

 (pi. 22, fig. 2, g, h, l-q), some of which are burned (pi. 22, fig. 2, n). 

 The great majority of the bones are small split fragments, most of 

 which possess a rich brown patination. One bone fragment (pi. 22, 

 fig. 2, m) shows the marks of some rodents gnawing and all are more 

 or less fossilized. The above objects are scattered at random through- 

 out the 3-foot gravel and shale stratum. Only two of the retouched 

 pieces can be classified as definite artifacts. These are a delicately 

 retouched side scraper with two sharp edges (pi. 22, fig. 2, e) and the 

 butt end of a rather heavy dart, spear, or knife point (pi. 22, fig. 2, ;'). 

 There are, however, large numbers of flakes suggesting crude artifacts 

 but too irregular for classification. Many of the large flakes show 

 no retouching of any sort and could have been caused by natural 

 agencies. The majority of the flint nodules encrusted with a limestone 



