Geoscience Reference
In-Depth Information
paleoceanographer James Kennett (see i gure 19), to reconstruct coastal sea sur-
face temperatures in the Santa Barbara Basin during the Holocene. Climate
conditions along the coast were not as severe as inland, and the high biological
productivity along the coast would have provided marine resources not available
in the desert interior. h e wetlands of California's Central Valley would also
have provided more resources and favorable conditions than the interior des-
ert regions. At a time when the Great Basin and southeastern California were
severely dry, the coast would have of ered increased food and water resources.
According to Douglas Kennett, archaeological evidence supporting
a coastal migration during the mid-Holocene comes from a study of the
distribution of language groups in western North America. In particular,
the Uto-Aztecan language family is distributed between coastal regions of
present-day Southern California, the Southern California desert, and much
of the Great Basin. h
is distribution suggests a movement of people from the
interior to the coast.
Other archaeological evidence suggests that populations from the dry
desert interior increased their interactions and trade with peoples along the
California coast and Central Valley during the mid-Holocene drought. h is
evidence is contained in shell mound deposits excavated along the central and
southern coasts, including the Santa Barbara Channel Islands. Exchanges
among the tribes may have buf ered the impacts of the drought, lowering
the risks of reduced resources that would have accompanied extended dry
conditions. Evidence for increased trade comes from beads crat ed from the
marine shell
Olivella biplicata,
or “purple olive snail.” During the mid-Holo-
cene, rectangular beads were cut from the body whirl of these snail shells
and used for trade and exchange. Specialized tools (micro-drills and anvils)
for fashioning these beads, as well as the debris from their manufacture,
were recovered on the Santa Barbara Channel Islands. h e beads have been
found in sites along the Southern California coast and in the northern and
western Great Basin. Based on the ages and contexts of these beads, their dis-
tribution suggests that new trade routes were established between 5,900 and
4,700 years ago—the driest period of the mid-Holocene.
expanding coastal environments
h e coastal environment was just beginning to stabilize starting about
6,000 years ago, in the midst of this mid-Holocene drought. h
e period that
