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Fig. 10.12
Tree-ring-reconstructed
summer PDSI during the
sixteenth-century
megadrought (see Fig. 10.2
for map details), the most
severe sustained North
American drought evident in
the tree-ring record for the
past 500 years (Stahle et al.
2000 , 2007 ) . Dry conditions
prevailed for 30 years
(1560-1589), but the
epicenter of decadal drought
shifted across the continent
during the late sixteenth
century (not shown)
Mountains (Stahle et al. 2007 ) . During its most intense phase, the sixteenth-century
megadrought appears to have exceeded the severity and geographical coverage of
the Dust Bowl drought and may have been the worst drought over North America
in the past 500 years (Stahle et al. 2000 ) .
Significant environmental and socioeconomic impacts of the sixteenth-century
megadrought have been reported for Mexico, the southwestern United States, and
the Spanish and English colonies in the southeastern United States. Sir Walter
Raleigh's colony on Roanoke Island (North Carolina) disappeared in 1587, which
tree-ring data suggest was the driest single year in 800 years for the Tidewater region
of Virginia and North Carolina (Stahle et al. 1998 ) . The Spanish colony at Santa
Elena, South Carolina, occupied during 1565-1587, endured many hardships asso-
ciated with drought during the 1560s. The Juan Pardo expedition into the interior of
the Carolinas and Tennessee during 1567-1568 was organized in part to seek food
supplies for the colony (Anderson et al. 1995 ) . In northern NewMexico, some pueb-
los were abandoned during the sixteenth-century drought (Schroeder 1968 , 1992 ) .
Many of these settlements relied on rainfall agriculture and evidently could not be
sustained during the extended drought.
The most severe impacts of the sixteenth-century drought appear to have
occurred in Mexico, where extreme drought interacted with conquest, colonization,
harsh treatment of the native people under the encomienda system of New Spain,
poor crop yields, and epidemic disease to result in one of the worst demographic
catastrophes in world history. The size of the native population of Mexico at the
time of European contact is controversial, with the low count of 'minimalists' such
as Angel Rosenblatt estimating some 8 million inhabitants, and the high count of
 
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