Northeast Subsistence-Settlement Change: A.D. 700 –1300

from their parent material. As these materials are
transported from one location to another they “pick
up” various impurities (or trace elements) that effect
the final composition of the clay. For this reason, the
composition of the clay represents a combination of the
specific stages of weathering as well as portions of the
parent lithology. According to Bishop et al. (1982:294),
“even in a region considered to be relatively homogeneous
in its gross geologic characteristic, significant
mineralogical and chemical differences may be diserned”
as a result of these processes. Secondary clays
are usually well sorted and exhibit a high degree of
plasticity due to their high organic content, making
them desirable to traditional potters (Rice 1987:37-38).
According to Pretola (2000:64-65), depositional clays
can be further classified based on the conditions of
deposition and transportation. Included among these
are glacial, lacustrine, and swamp clays.
The glacial lake clays that characterize the Northeast
possess ideal qualities for traditional non-wheel manufacturing
and firing (Brownell 1951:17; Pretola 2000).
According to Rice (1987:37), glacial lake clays, which
are characterized by their course, organic-rich texture,
contain properties that are conducive to prehistoric
manufacturing techniques, which involve repeated
episodes of forming and drying. In addition, these
clays are well suited for the open firing techniques preferred
by prehistoric potters, since they require ceramic
pastes that can withstand the thermal shock produced
by uneven heating and cooling (Pretola 2000:65).
The selection of clays by prehistoric potters was
probably not haphazard, but represented a balance
between technical and nontechnical choices. Quality is
one of the leading factors in the selection of clays. In
their study of Kalinga ceramics, Aronson et al.
(1994:90) indicate that potters preferred to use clays
with little or no mineral inclusions and a high degree of
plasticity. Accessibility and distance were also important
factors in selection; potters preferred to procure
materials from deposits near their house or within a
familiar political region. This information seems to
coincide with Arnold’s (1981:36) estimates that most
clays were procured from deposits located less than 50
km from one’s residence.
Ceramics are composed of a clay matrix and nonplastic
inclusions (or temper). Nonplastic inclusions
often consist of larger (greater than 20 m or 0.02 µm in
diameter) minerals and rock fragments, such as quartz,
feldspar, and gneiss, which are added to the clay
matrix to counteract the effects of shrinkage during
drying and firing. Inclusions less than 20 µ (or 0.02
mm) in diameter (e.g., fine silt and sand) are usually
naturally occurring materials that were present in the
clay deposit (Bishop 1980:49). It is usually difficult to
determine whether the small inclusions found in pottery
are naturally or intentionally deposited. According
to Shepard (1995:161), the only sure way to know is to
determine which materials do not occur naturally in
the clay.
Because clay used in producing ceramics contains
natural or intentionally added inclusions, compositional
studies must take into consideration the effect that
these inclusions will have on the larger compositional
profile. Different inclusions will interact differently
with the clay (Bishop et al. 1982:295; Cogswell et al.
1998). Some inclusions, including “pure” quartz sands,
alter the chemical make up of the sherd, lowering trace
element concentrations. Other elements (e.g., zircon)
result in a complex interplay of elements, where the
frequency of some elements is increased while that of
others is lowered. Other inclusions, including quartz
sand, calcite, limestone, and some kinds of vegetal
fiber, appear to have little or no effect on the compositional
profile.
Finally, other manufacturing activities may also
affect the composition of the ceramic paste. Among the
more problematic activities is the mixing of clays from
several different deposits in order to achieve a desired
plasticity (Arnold 1985; Aronson et al. 1994:90-91; Rice
1987; Shepard 1995). As discussed by Bishop et al.
(1982:317-318), this often occurs when residual and
depositional clays are mixed, resulting in a chemical
“fingerprint” that often does not match the compositional
profiles of known or naturally occurring lithological
deposits.
Although compositional studies prove useful when
analyzing prehistoric pottery, to date, only a handful of
studies have been completed in the Northeast.
Included among these are studies by Trigger et al.
(1980:119-133, 1984:3-11), Crepeau and Kennedy
(1990:64-65), and Stimmell et al. (1991:47-58), which
focus on the production of ceramic vessels and their
place of manufacture within isolated parts of Ontario,
Quebec, and Manitoba. Studies of St. Lawrence
Iroquoian pottery by Trigger et al. (1980) and Crepeau
and Kennedy (1990) produced data that exhibit a high
degree of compositional homogeneity within sites,
suggesting that a limited number of clay deposits were
exploited by the site’s occupants. Although the results
of both of these studies indicate that St. Lawrence
Iroquois pots were locally manufactured, Trigger et al.
(1980:132) indicate that pots from different longhouses
produced different compositional profiles, suggesting
that different households may have exploited different
140 Rieth