NO. 10 NEBRASKA ARCHEOLOGY STRONG 227 



country rocks. These consist, on an average, of 8 feet of fine wind- 

 borne material. Essentially, these may be called loess deposits, for 

 analyses show their composition to be very similar to that of true 

 loess found farther eastward. This loessial material is divided at 

 intervals by three horizons of human cultural debris (numbered 

 I-III from bottom to top). These intrusions represent old soil and 

 living levels. The lowest cultural horizon, level I, lies directly on 

 what are believed to be fluvial silts and gravels (fig. 29 and pi. 23, 

 fig. 2). It is composed of loess similar to that of the rest of the aeolian 

 portion of the earth cap impregnated with artificial matter, and con- 

 tains humus to the extent that the horizon presents a sooty blackness. 

 Some blackness may be attributable to burning, but a soil horizon is 

 undoubtedly present. The horizon is so solidly cemented together by 

 calcium carbonate that a shovel will not make much headway in it. 



Above level I (fig. 29 and pi. 23, fig. 2) lies a i^-foot horizon of 

 sterile wind-borne material. Occupation of level I must have ended 

 abruptly, as shown by the sharp transition into the sterile layer above. 

 Above this sterile layer is a thin dark horizon (level II, fig. 29, pi. 23, 

 fig. 2) about 6 inches thick. This horizon is darker than the sterile 

 layers above and below, and it contains small amounts of rocks, bones, 

 artifacts, and a few fireplaces. Level II is capped in the center by 

 about 2 feet of sterile wind-borne material, and this in turn is covered 

 by about i^ feet of soil containing artificial matter (level III). At the 

 surface a vigorous growth of prairie grasses has darkened the soil to 

 a depth of 3 or 4 inches. Level I lies in a flat plane, as does also level 

 II some 2~ifeet above, but level III lies arched or draped over the 

 present surface and, as a result, almost makes contact with level II at 

 the edges of the deposit (fig. 29). 



METHOD OF EXCAVATION 



Before excavating, a topographic map was made of the butte by 

 means of a plane table and telescopic alidade. The earth cap was con- 

 toured, using i-foot intervals, the remainder of the butte was done in 

 lo-foot intervals, and later a topographic map showing the 4 square 

 miles around the butte, on a scale of 1,000 feet to an inch with lo-foot 

 contour intervals, was made. The top of the butte was surveyed and 

 staked off into 5-foot squares, and excavation proceeded on a 20-foot 

 front from south to north. Later an east to west excavation was made, 

 tying in with our original test trench. Every cross-section was mapped 

 as exposed. The work was confined to the western half of the butte, 

 the entire eastern half being left for future excavation and checking. 

 The deposit was taken down layer by layer, according to squares, and 



