208 



THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



to 1610, and at this same time Mexico suffered from two phenomenal inundations. There- 

 after there came a brief dry period in Mexico marked by drought and famine in 1608 and 

 again in 1615. This does not appear in the California trees, whose growth merely ceases 

 to increase in rate, but still remains high. It is quite possible, however, that these par- 

 ticular years were bad years in California, but that theu" effect is concealed by the good 



Table 10. 



Year. 



1440(7) 



1498 



1519 



1523 

 1553 



1580 

 1604 



1607 



1023 

 1629 

 1645 

 1648 

 1675 

 1G91 



1697 



1707 

 1732 



1748 

 1762 



1772 

 1795 



Authority. 



Conditions in Mexico City. 



Conditions of tree growth in California. 



Torquemada Great inundation. 



Humboldt. 



Humboldt Inundation. This has no great sig- 

 nificance, because it was due to the 

 mistaken policy of turning the 

 Huitzilopoche River into Lake 

 Tezcuco. 

 Do Inundation 



Cavo, p. 25... 



Humboldt 



Torquemada. 

 Cavo, p. 109. 



Humboldt 



Do 



Torquemada. 



Humboldt 



Torquemada. 

 Cavo, p. 162. 



Cavo, p. 175 



Himiboldt; Cavo,p.l83. 



Cavo, p. 196 



Humboldt 



Do 



Cavo, p. 233 



Do 



A famous inundation. According to 

 Cavo a drought was broken by a 

 violent rain that lasted not quit« 

 24 hours and inundated the whole 

 valley of Mexico. Such inunda- 

 tions (according to Bandelier) were 

 at that time frequent and were not 

 regularly recorded on account of 

 being looked upon as a common 

 occurrence. 



Inundation 



Famous inundation 



Great inundation. , 



Cavo, p. 240 . 



Humboldt. 

 Do... 



Do 



Cavo, p. 293 . 



Humboldt . 

 Do... 



Inundation in December 



Inundation. Great rains 



Inundation 



Do 



Do 



Inundation and also hea\'y frosts 

 unusually early. 



Inundation . 



Do, 

 Do. 



Do. 



Overflow of Lake of Mexico. 



Inundation . 

 Do 



Relation of Mexican lakes 

 and California trees. 



Slight decrease in rate of growth com- 

 pared with previous decade, but 

 during this general period a very great 

 'decrease changes to essential uni- 

 formity. 



Slow, but steadily increasing 



Neutral. 



Agreement. 



Mediimi in amount and rapidly in- Do. 



creasing. 



Medium and only slightly increasing . . , Neutral. 

 Rapid with great increase Marked agreement. 



Medium with moderate decrease Disagreement. 



Rapid growth and great increase Marked agreement. 



Do. 



Rapid, but beginning to decrease 



Do 



Medium, but with sUght increase 



Do 



Rapid and increasing 



This decade was characterized by 

 marked decrease, but at its beginning 

 the growth was very rapid, so that it 

 is impossible to determine whether the 

 first year of the decade was character- 

 ized by slow growth or fast. 



Same as preceding, but as this year 

 comes toward the end of the decade 

 it probably should be counted as 

 distinct disagreement. 



Slow with rapid decrease 



Moderately rapid, and with rapid in- 

 crease. I 



Rapid with marked increase \ 



Fairly high, but rapidly decreasing. 

 This case may be like that of 1691, 

 but it is better to reckon it as dis- 

 agreement. 



Low but with a distinct rise 



Moderately rapid with great increase . . 



Do. 



Neutral. 

 Do. 

 Do. 

 Do. 



Agreement. 

 Neutral. 



Disagreement. 



Pronounced disagreement, 

 Agreement. 



Pronounced agreement. 

 Disagreement. 



Agreement. 

 Do. 



The following occurrences of dry times should be mentioned in connection with the table: Cavo (p. 109) states 

 that the violent floods of 1553 followed a drought, but it is not evident whether the drought was of any importance. 

 In 1608 (p. 164) after the great floods of 1604 and 1607, he speaks of another drought followed by the receding of the 

 lake in 1609, while in 1615 (p. 171) he records a drought and famine. Both of these must be regarded as distinct dis- 

 agreements. In 1750 (p. 2S7) he records famines in northern Mexico, but good crops south of Guanajuato. This 

 comes at the end of a time of rapidly increasing growth in the trees, but is not distinct enough to be counted, except 

 as neutral. 



years before and after them. In the next decade, 1621 to 1630, we find the trees still 

 growing rapidly, and in Mexico City there were two inundations. Thereafter the trees 

 dechiie, but only a little. In the decade from 1641 to 1650 their growth revives very 

 slightly, and in Mexico there were two inmidations, neither of them of the first importance. 



