740 Notice of some Human Remains ` (August, 
heaval before consolidation, a circumstance which an examination 
of the ground further verifies. The bones present a yellowish 
appearance and the characteristic aspects of fossilization, it being 
noteworthy that they are not coated with layers of the calcareous 
rock as is observed in the recent deposits, but are firmly imbed- 
ded in the stone, which also fills the cells of the tissue. 
Several distinct formations and rocks are seen in the locality 
where the bones were found; towards the center rises the small 
hill “ del Peñon,” consisting of volcanic porphyries; on the base 
to the north there appear first a clearly recent formation made up 
of vegetable earth, marl and ceramical remains, which in the 
upper part are modern, and in the lower belong to the Aztec 
ceramics. Under this recent formation are the calcareous layers 
in which the human remains were found. 
These layers crop out with a rise toward the northern bound- 
ary, forming the end of an esplanade which surrounds the hill, and 
is three meters above the actual level of the waters of Lake Tez- 
coco. The layer of hardened rock does not extend with regu- 
larity the whole distance from the before-mentioned edge to the 
foot of the hill, some intervening spaces occurring in which this 
rock does not appear; the resulting hollows being filled with 
recent ground. This circumstance as well as the appearance of 
the layers of calcareous tufa, prove that this rock was upheaved 
after the deposit of the human bones, by the igneous rocks which 
crop out in the neighborhood of the hill forming dykes. This 
upheaval is also verified by the numerous smalls veins which are 
found in different directions on the ground. 
In order to clearly establish the age which the deposit of the 
human bones might have, the best scientific method would be to 
find some animal fossil remains in the same formation which 
would distinctly mark the age of the layers of that calcareous 
rock, but until now, notwithstanding the many searches made, it 
has not yet been possible to find any traces of extinct animals; 
_ neither has there been found any vestige of ceramics or other re- 
mains that might indicate that these rocks were clearly modern, as 
among them the only things found were the human bones, roots 
converted into menilite and some small indeterminable lacustrine 
shells formed by the same calcareous substance. These shells 
L . belong to genera which have lived in Quaternary as well as ins 
eee 
: a sa waters, it ae: been Sos to determine their species 
