KNOWLEDGE ♦ 



tliey are not coated with layers of the calcareous rock 

 as is observed in the recent deposits, but are firmly 

 imbedded in the stone, which also fills the cells of the 



Several distinct formations and re 

 localitj- whore the bones were found ; 

 rises the small hill, " del Peiwn," eoi 

 porphyries ; on the base to the i 

 a clearly recent formation made 

 marl, and ceramical remains, \\\ 

 are modern, and in the lower 

 Under this recent f..; 



cks are seen in the 

 towards the centre 

 isisting of volcanic 

 jrth there appear first 

 ,p of vegetable earth, 

 eh in the upper part 

 belong to the Aztec 

 nation are the calca- 



e toward the northern 

 esplanade which sur- 

 metres above the actual 

 level of the waters of Lake Tezcoco. The layer of 

 hardened rock does not extend with regularity the whole 

 distance from the before-mentioned edge to the foot of 

 the hill, some intervening spaces occurring in which thf 



These layers ( 

 boundary, formi 

 rounds the hill, 



e end of a 



and i 



rock does not 



with recent ground. This 

 appearance of the layers of 

 this rock was upheaved afte 

 bones, by the igneous r.ieks i 

 bourhood of the hill, fni-ini 

 is also verified by th( 

 found in different directions 



In order to clearly establish th 

 of the human bones might h: 

 method would be to find some a 

 the same formation which won 

 :ige of the layers of that calearei 

 notwithstanding the manj- scm' 

 yet been possible to find any t ■ 

 neither has there been fouml i- 

 other remains that might indi' : 

 clearly modern, as among them 

 were the human bones, roots con' 

 -some small indeterminable lacu 

 the same calenreous substance. 

 genera whicb 

 waters, it h: 



being filled 

 istauce, as well as the 

 eous tufa, prove that 

 lejjosit of the human 

 ■iMp out in the neigh- 

 kes. This upheaval 

 imall veins which are 

 the ground. 



age which the deposit 

 re, the best scientific 

 inial fossil remains in 

 1 distinctly mark the 

 is Toek ; but until now, 



1|. - -r:. ..]■'. it ; 



..f t 



.species on ac 



which they were tound. 



In the region to the .south of th 

 calcareous rocks are seen, and thicke 

 ground with remains of Aztoe eerani 



Not being, therefore, abl.' to utilis. 

 data for determining < lie i-.-r of il,, 



e must fall back on the iii>|ii ri ioi 



t animals ; 



he only things found 

 ted into menilite, and 

 i lacustrine shells formed by 

 lice. These shells belong to 

 Quaternary as well as present 

 ipossible to determine their 

 bad state of preservation in 



Two far 



hill more modern 

 depiosits of recent 



the pula'ontological 

 e eMeai-eous layers, 

 f 1 1,.' -round. 



the for 



■ ].r, 



iid :, 



and the 

 bones a 

 that eo 



thr ' 



Il th.. , 



the lak 



In the first" eiise it eouM 1 1 



by a violent filtration of tli^ , 

 tion ; but nowhere in the vallr\ 

 to be found of a crack or oji. ;; 

 waters could have escaped, and v. 1 

 outside of the present level of thi 

 below, all the water would have disappeared. 



ioned cither 

 low evapora- 

 i-e any traces 

 li which the 

 hi to appear 

 *s. if it were 

 If the 



lowering of levi 1 ■/. 4' 

 wouldbemor.. ,: I' , 

 conquest of 'M^ \ i 

 have notably ili]..;u. ! 

 elapsed in order thai : 

 three metres to its ) r 

 long. What is most i 

 due to volcanic action ; t 

 has been discovered in 

 occupied by the harden- 

 are to be seen in differ. 



aporation, a theory which 



ise from the time of the 



',t the submerged surfaces 



tiirii- Tieeessary to have 



lake might fall 



have been very 



the upheaval is 



,.hiil now no basalt 



i ruoath the place 



■ , ■ Jvkes of that rock 



the foot of t 

 hill, and even the volcanic musses which constitute it are 

 found upheaved and inclined, demonstrating the succession 

 of geological phenomena in that vicinity. 



Let us now trace the origin of the silicificd calcareous 

 rock in which the bones were found, and which is different 

 from the majority of the lacustrine rocks which occupy 

 the valley of Mexico, these latter being, for the most 

 part, thick and extensive layers of pumice, tufas, marls, 

 volcanic ashes, clays, and alluvioi!^. 



In order to proceed with mor.- e-,iainty in this inves- 

 tio-ation, I compared the ( ;!^■a^el.u^ rock in question with 

 those which re>ei!;hh 1 :• n -. from other parts of Mexico, 

 and found it - usidered similar to those 



which are clear' ' ' ■' liermal origin. 



The hot-wat,i- .Ilia.' ulaah exists in the eastern part 

 of the hill del refion forms sel ■ '-i similar 



to the silicified calcareous tufa : u a small 



scale, and their formation is >- hide the 



belief that this sprin.j- could ha\ . .: immediate 



surroundings of the hill with deposits of such magnitude. 

 "What ismostprohahle is, that in remote times there were 

 great emissions of niiii,iMl thermal waters through dif- 

 ferent fissures, and m several directions, whose appearance 

 was simultaneous with the basaltic masses that form 

 dykes at the foot of the hill, as in the faces of the rocks 

 sedimentations similar to the referred ones are perceived, 

 there being, furtlien.iore, many small veins which cut 

 through the Ija^ali ie iaa». . and even the calcareous rock. 



By this it is seou that a ^eries of vocanic phenomena 

 must have taken place in that spot, beginning before the 

 human remains were deposited, and which further con- 

 tinued when the material which received them was but 

 little con.solidated. 



The succession of these phenomena took place, without 

 doubt, in the following wtiy : — 



L Emissic-in of thermal waters and appearance of ba- 

 saltic rocks, upheaving the masses that formed the hill. 

 These waters mixed with those of the lake which sur- 

 rounded the hill and extended over a lar-e area of the 

 valley of ilexico ; the calcareous depo.-its gi-.idually ac- 

 cumulated around the hill, and beii)- snll >..f. the human 



; (i.'i 



. ^Vhe 



the 



\\hieh were left after this upheaval, 

 h ; M>its were formed, which i] 



It 1> 



Of Mr 



of two metres above the present ground among rocks of 

 the hill del Tepeyac, north of the City of Mexico. 



