104 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 146 
of great importance. The Valliserrana area includes valleys and slopes 
between 1,200 and 3,000 meters in elevation. Rainfall is moderate, 
averaging about 300 mm. per year. Irrigation was extensively em- 
ployed, especially for the growing of maize. Pumpkins, beans, and 
potatoes were secondary crops, providing a varied diet. Agriculture 
was supplemented by llama herding. Wild fruits were collected, and 
hunting was a supplementary source of meat. The Selvas Occiden- 
tals, with low hills representing the last extension of the Andes and 
a dense subtropical forest vegetation, offer very different environ- 
mental conditions, which are reflected in the cultures that occupied 
this subarea. 
It is difficult to undertake a synthesis of cultural development in 
northwestern Argentina, and more so to identify the causal factors. 
One reason for this is the scarcity of comprehensive studies, leaving 
many regions completely unknown or only superficially investigated. 
Furthermore, even in many of the better-known areas no stratigraphic 
work has been done and no absolute dates are available. Other diffi- 
culties derive from the fact that Argentina occupies a position mar- 
ginal to the great South American nuclear center. It represents a kind 
of frontier for agricultural and pottery-making traditions, bordering 
on the hunting and gathering cultures of the Chaco, the Pampa, and 
Patagonia. Water routes beginning with the Parana and Paraguay, and 
ascending the Salado and tributaries of the Bermejo into the very 
heart of northwestern Argentina, made the region subject to strong 
influences from the Tropical Forest cultures of Amazonia. 
As a result of these complications, deriving both from marginality 
of geographical position and incompleteness of archeological informa- 
tion, any developmental framework of periods established for the 
nuclear area or areas of South America is difficult to apply to north- 
western Argentina. Although the principal cultural component is un- 
doubtedly of Andean origin, at certain times in the history of the area 
important roles were played by cultures adapted to the river and 
forest environment, which is very different from the Andean type. 
These traditions met and mixed, producing results distinct from the 
pattern farther to the north in the Andean Area. Also, the marginal 
geographical position had the consequence that cultural influences 
from the north must typically have arrived after a certain amount of 
lag in time, so that cultural stages representing a more or less well 
defined time period in the Central Andes cannot be projected onto 
northwestern Argentina without clear recognition of the lack of con- 
temporaneity in the traits involved. 
