THE ARCHAIC HORIZON 45 
is of greater thickness and the archaic layer of lesser 
thickness. The remains extend below the present level 
of the water and may indicate that considerable changes 
have taken place in the level of the lake. But we must 
remember that many of the ancient settlements were 
10 
Temple mounds of Tol- 
tecan period. 
Surface finds of Aztecan 
period. 
Remains of Toltecan 
period. 
Deep stratum of water- 
bearing gravels contain- 
ing remains of archaic 
period. 
Bed rock of hard clay. 
Fig. 11. Diagram of Culture Strata at Atzcapotzalco. 
built over the water and that land was made in ancient 
times, as it is today in the gardens of Xochimilco, by 
deepening canals. Archaic remains are also common on 
the denuded tops of hills which may once have been 
covered by soil. 
