Idaho National Laboratory Cultural Resource Management Plan

INL (Marler 2004; Reed et al. 1987a, 1987b).
Birch Creek points were found in direct
association with a series of 8000-year-old bison
kills at the Wasden site and Owl Cave (Butler
1978, 1986; Miller 1982) and at Bison Rockshelter
and Veratic Rockshelter in the Birch Creek valley
(Swanson 1972). Evidence from all locations,
dated or not, suggest that the people who used
these points were relying heavily on animal
species such as bison and mountain sheep, which
survived the transition from the Pleistocene to the
Holocene epoch.
Middle Prehistoric Period: 8000 to
1300 B.P.
The close of the early prehistoric period and
the beginning of the middle prehistoric period was
marked by a major change in projectile point
structure and form, probably corresponding to a
major shift in hunting technology. Large spear
points characteristic of the earlier period were
almost entirely replaced by smaller notched and
stemmed forms. This transition probably
represents the adoption of an atlatl (i.e., spear
thrower) technology, which may have been more
effective in exploiting newly evolved species that
survived the Pleistocene-Holocene transition. The
presence of ground stone in middle prehistoric
contexts at some sites such as Wilson Butte Cave
(Gruhn 1961) and the Birch Creek Rockshelters
(Swanson 1972) also suggests that plant foods
such as camas may have gained increased
importance during this time. However, available
evidence suggests that hunting remained a
dominant economic endeavor. Thus, the middle
prehistoric period on the eastern Snake River Plain
was marked by some changes in lifestyle, but it
did not represent a major break from the previous
early prehistoric period.
The environment during the middle prehistoric
period was one of transition. A general warming
trend continued, reaching a point of maximum
warmth and dryness at approximately 3800 B.P.
(Currey and James 1982), but available evidence
seems to indicate that these conditions did not
produce dramatic environmental changes in the
area. Pleistocene Lake Terreton probably declined
to its present seasonally marshy state, and the
internal playas held little, if any, standing water.
However, pollen profiles indicate that modern
xeric (i.e., dry) vegetation was present throughout
the interval (Davis and Bright 1983). This
essentially modern habitat supported many
animals that were of economic importance to
human populations, including modern bison and
antelope on the grasslands and mountain sheep,
elk, and deer in the higher elevations.
Middle prehistoric projectile point forms
suggest that this was a time of some cultural
reorganization and mobility. The archaeological
record reflects this in a proliferation of point
styles, which appear to have correlates in both the
northwestern plains and the Great Basin. It appears
that people from these surrounding areas were
moving in and out of the eastern Snake River
Plain, perhaps in response to deteriorating
environmental conditions (Benedict 1979; Madsen
1982).
The diagnostic time markers of the initial
portion of the middle prehistoric period are
Bitterroot or Northern Side-Notched points
(Greiser 1984; Gruhn 1961; Swanson 1972) and
sporadic stemmed-indented base points that
resemble the Pinto series of the Great Basin
(Holmer 1986a). Both forms occur in prehistoric
contexts ranging from 8000 to 6000 B.P. at sites
such as the Birch Creek Rockshelters (Swanson
1972) and further south at Weston Canyon
Rockshelter (Miller 1972). At both of these sites,
mountain sheep appear to have been the preferred
prey in an economy that continued to be focused
on the acquisition of game animals.
Between approximately 6000 and 3500 B.P.,
large side-notched points decreased in frequency,
and around 5000 B.P., stemmed-indented base
points became the dominant style of dart in the
region. Large corner-notched varieties and new
small lanceolate forms also made their first
appearance around 4000 B.P., but did not become
dominant until later (see Figure 11). Once again,
mountain sheep and bison appear to have been the
favored game.
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