THE FALL OF THE OLD EMPIRE. 451 
“According to our hypothesis the high parts of the curve mean abundant 
rainfall in southern California, but diminished rainfall and a pronounced dry season 
in the Maya area. Therefore they are the favorable periods. The low shaded 
areas [the black sections, below the line ab in figure 71, the level of present pre- 
cipitation], on the contrary, indicate times of drought in California, but of abund- 
ant rain at all seasons in the Maya area, with consequent dense forests, difficult 
agriculture, overwhelming disease, and enervating damp heat at all times.” 
During the first five hundred years before Christ and down to the be- 
ginning of the third century after Christ, when it is necessary to assume 
the Maya were developing their peculiar culture and remarkable calendar 
and chronologic system, extremely favorable climatic conditions, denoted by 
the general height of the curve above the line ad in figure 71, seem to have 
prevailed between 14° and 18° north latitude, the region of the Old Empire 
civilization, according to Huntington’s hypothesis. 
It will be noted further, that beginning with the third century after 
Christ, a steady decline in the curve sets in, which continues with but few 
minor variations until the middle of the fifth century. That is to say, 
according to the writer’s correlation of Maya and Christian chronology, the 
climatic conditions during the Early and Middle Periods grew steadily worse, 
although up to the early part of the Middle Period they were still fairly good. 
By the middle of the fifth century, however, the annual rainfall had become 
as heavy as it is to-day in this region, a fact indicated by the curve having 
dropped to the horizontal line ad in figure 71, and living conditions, accord- 
ing to Huntington’s hypothesis, had become intolerable. At this point, 
however, the curve sweeps upward and so continues with few minor varia- 
tions for nearly a century, until 540 a. p., indicating a return of favorable 
climatic conditions to the southern Maya area, and in the writer’s correla- 
tion of the two chronologies, coinciding with the last katun of the Middle 
Period and the first two and a half katuns of the Great Period, the katuns 
of maximum sculptural and architectural activity. 
From 540 to 560 (approximately 9.18.10.0.0 to 9.19.10.0.0, according 
to the writer) the curve again makes a sudden drop to the unfavorable level 
of present conditions, and then rises rapidly between 560 and 610 (approxi- 
mately 9.19.10.0.0 to 10.2.0.0.0, according to the writer), only to drop as 
suddenly to new low levels after 610, indicating heavier annual rainfall and 
more unfavorable conditions than even to-day, which continued for more 
than two and a half centuries. And just here is perhaps the most satisfac- 
tory agreement between the dates on the monuments and Huntington's 
diagram. No two katuns of the Middle and Great Periods are represented 
by fewer monuments than the two between 9.19.0.0.0 and 10.1.0.0.0 (551 to 
590); indeed, there are only two monuments now known (Stela D at Nakum 
and Stela 32 at Naranjo) which date from this period. The beginning of 
this lacuna in the monumental sequence falls almost in the middle of Hunting- 
ton’s second minimum after the birth of Christ, and under his hypothesis is 

1 Huntington, 1917, p. 158. 
