452 THE INSCRIPTIONS AT COPAN. 
to be interpreted as indicating a falling-off in the erection of stele owing to 
the prevalence of extremely unfavorable climatic conditions. A number 
of monuments, however, were erected in 10.1.0.0.0 and 10.2.0.0.0 (591 to 610 
according to the writer), which Huntington would have us believe was due 
to a return of more favorable climatic conditions, evidenced by the contin- 
uous rise of the curve from 560 to 610. Finally comes the sudden cessation 
of all monuments in the Old Empire after 10.2.0.0.0 (610 A. D. according to 
the writer), evidenced by a drop of the curve to new low levels of unfavora- 
bility and its continuance there for the next two and a half centuries, during 
the first part of which period the Maya are known to have abandoned the 
southern cities, as Huntington believes, due to the prevalence of the worst 
climatic conditions they had ever experienced. 
In spite of these satisfactory, not to say almost startling, agreements, 
the writer feels unable to accept this hypothesis as the principal explanation 
why the Maya abandoned such a large region as that covered by the Old 
Empire, although admitting that climatic changes may have been partially 
responsible therefor. 
The principal objection to Huntington’s hypothesis, as already pointed 
out, is not his data on the variation of rainfall in southern California, which 
appear to be fairly well established by the varying thickness of the rings of 
the Sequoia washingtoniana, nor is it so much a question of possible inac- 
curacy in the writer’s correlation of Maya and Christian chronology, which 
now appears from all indications to be correct with a maximum margin of error 
of not more than one year (see Appendix II), but rather uncertainty as to the 
accuracy of his basic postulate that climatic changes in southern California 
were accompanied by and coincident with diametrically opposed changes 4,000 
kilometers distance to the southeast. This is a far-reaching and fundamental 
assumption, and even in spite of the apparently corroboratory results recently 
obtained by Penck, Arctowski, Helland-Hansen and Nansen, Hildebrands- 
son, and Brooks in this field, it seems safer to withhold unqualified accep- 
tance thereof until the laws governing climatic changes have been more 
thoroughly worked out than at present, and their nature and operation more 
clearly understood. 
There remains to be considered but one more hypothesis, which seeks 
to explain the extinction of the Old Empire civilization, namely, that sug- 
gested by Cook,' that the system of agriculture practiced by the Maya 
eventually reduced the soil to such a state of unproductivity that they were 
literally starved into moving elsewhere. He sums up his conclusions in the 
following words: 
“Apart from dangers of war or pestilence to which the ancient communities 
of Central America may have been exposed, their existence was definitely limited by 
methods of agriculture which denuded the country of its forests, and destroyed the 
fertility of the soil. Civilization is at an end when an agricultural country ceases 
1 Cook, 1909. 
