GUATEMALA AND THE HIGHEST NATIVE AMERICAN CIVILIZATION. 215 



true here, and if we further assume the correctness of our previous conclusions as to the 

 synchronism of wet times in California and dry times in Central America, we may frame 

 the following tentative table on the basis of the curve of growth of the sequoias: 



(1) Previous to 100 b.c. Period of aggradation and presumably of increasing aridity antecedent to the building 



(2) 100 n.c.-25o' a.d. Period of high river-level, but not of much change of level in fiood-plain, that is, a time 



when, although aridity was no longer increasing, there was no special tendency toward more moisture. 

 Building of Copan. e , ,„ r ii. i • 



(3) 250-700 A.D. Period of degradation or downcutting by the river up to the edge of the 18-foot terrace — that is, 



a time when the amount of rain and of vegetation was increasing. Occupation of Copan followed by 

 decUne and abandonment. The date of the last monument is about 500 a.d. according to Spinden and 

 230 A.D. according to Bowditch. ■ a j i • * 



(4) 700-1000 A.D. Period of aggradation and of increasing aridity during which the river built up its flood-plain to 



the 12-foot level. , . , . , , . , 



(5) 1000-1300 A.D. Period of degradation and of increasing moisture with deepening of river channel in such a 



way as to form the 12-foot terrace. , . . „ , 



(6) 1300-1900 A.D. Period of minor fluctuations of climate with alternate deposition and erosion, the present Hood- 



plain being api)roximately the mean level. 



In a table such as this the possibility of error is great, for the number of unknown 

 factors is large and many assumptions must of necessity be made. I do not present it as 

 in any way final, or as more than a mere suggestion of the way in which, when far fuller 

 information is available, we may perhaps be able to correlate such diverse phenomena as 

 changes of climate, variations in the activity of rivers, and events of history. Its present 

 importance lies in the fact that when we submit our climatic theories to the severe test of 

 a comparison between the growth of trees in California and the activity of rivers in Guate- 

 mala, we at least find no obvious contradiction. 



Leaving, now, this rather speculative matter, we may briefly sum up the evidence of 

 the terraces. Tw^o points stand out clearly : 



(1) There can be no question that in Guatemala we find terraces of the kind that our 

 climatic theory would lead us to expect. The only surprising thing is that they occur in 

 places where the vegetation is denser than we should have anticipated, which suggests that 

 if climatic changes have occurred, they have affected vegetation in moist tropical regions 

 more than in moist temperate regions. 



(2) The terrace-making process has been active since the foundation of Copan, one of 

 the chief of the ancient Maya towns, but the activity has been mild compared with that of 

 earlier times. If the tectonic theory of alluvial terraces is correct, these two points have 

 no special significance. If the climatic theory is correct, they add much to the reliabiUty 

 of our main conclusions. 



We come now to a subject much more significant than the terraces. In Guatemala the 

 former distribution of population and still more of culture was utterly different from that 

 of to-day. Aknost nowhere else in the whole world have 2,000 years or less produced so 

 profound a change as in this little country of only about 48,000 square miles. The normal 

 decay of races, the interplay of historic forces, the invasion of barbarians, the decadence 

 due to luxury, vice, and irrehgion, the change of the center of world power, each or all of 

 these causes, or any others usually appealed to by historians, can not explain the matter. 

 The question is not why the Maya civilization arose, nor why it fell. We may assume 

 that it arose because it is the nature of a young and vigorous race to make progress, and 

 that it fell because it is the nature of an old and exhausted civilization to decay. The 

 assumption does not help us in the least, for it does not touch our problem. To-day the 

 most progressive and energetic people of Guatemala, its densest population, its greatest 

 towns, its center of wealth, learning, and culture, so far as these things exist, are all located 

 in the relatively open, healthful, easily accessible and easily tillable highlands; in the past 

 these same things were located in the most inaccessible, unhealthful, and untillable low 

 lands. Why the change? 



