90 BUREAU OF AMERICAN ETHNOLOGY : [BULL. 33 
(6) Observing the condition of the bones, it is noted that the color, 
surface markings, consistency, discolorations, and other characteris- 
tics are much the same at all levels; the differences are no greater 
than those observed in the different parts of a single skull or in 
specimens in immediate proximity to one another. Such could 
hardly be the case if some of the bones were thousands of years more 
ancient than others. The chemical action of the soil, coupled with 
that of organic elements within it, on human bones in some instances 
may be very slight, yet it is incredible that no marked differences 
should be perceptible in the effects of these agencies on bones of the 
Glacial or the immediately post-Glacial period and those of recent 
centuries. 
This brings us directly to the very important concurrent fact of 
the total absence from any of the bones of perceptible fossilization. 
Such a condition would be hard to explain in bones dating from the 
period of the original loess deposit and under the circumstances in 
which the specimens in question were found. It is true that minor 
grades of mineralization, which may be difficult of detection, occur in 
rare instances in certain pleistocene sands or in perpetually dry cave 
deposits, but the fine Nebraska loess presents different conditions. 
The fire-hardening at one of the higher levels in the mound was not 
sufficient to keep out moisture and air, whose presence facilitates 
physical and chemical changes in inclosed bones. At the time of our 
visit to the locality in January the earth was found to be frozen at a 
level lower than the baked layer. To overcome this difficulty of 
absence of perceptible mineral replacement, and even of infiltration 
of the specimens, those who would prove that the deeper-lying bones 
from the Gilder mound are geologically ancient should produce satis- 
factory specimens of bones, unquestionably ancient yet nonfossilized, 
from deposits of the same nature and existing under the same con- 
aitions. 
Only one piece, the fragment of a lower jaw, shows changes such 
as could have been produced by exposure to the elements, even for 
a moderate length of time. On none of the other bones do we find 
the easily recognizable results of bleaching or cracking caused by 
exposure to the sun, or of superficial abrasion that could be attrib- 
uted to water action. The etching or pitting of the surface observed 
in some of the bones is due to the action of minute roots or to corro- 
sion by chemical agencies in the soil or in percolating waters. 
These features are common to bones embedded for even short periods 
in various soils. 
(c) Numerous bones from the different levels show marks due to 
the gnawing of rodents and also cuts made by some sharp implement 
wielded by human hands. The tooth marks indicate that at some 
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