Abstract:
ABSTRACT
GROWTH INCREMENT ANALYSIS OF ARCHAEOLOGICAL
FRESHWATER MUSSELS FROM INTERIOR NORTHERN
CALIFORNIA
by
Deanna M. Commons
Master of Arts in Anthropology
California State University, Chico
Spring 2010
The purpose of this study is to evaluate the accuracy and reliability of a shell
growth increment measurement technique that was developed by James C. Chatters for
use on modern and archaeological freshwater mussel specimens. Freshwater mussels
have been an important food resource for Native American groups in Northern California
for thousands of years. The freshwater mussels uncovered at archaeological sites
can be used to estimate seasonality. While four other shell growth increment measurement
methods have been developed and used more widely, these techniques lack applicability
to archaeological specimens and result in inaccurate estimations.
To evaluate Chatters’ increment measurement technique, I applied the
method to a sample of modern freshwater mussels. This was to determine if the collection
date of the sample of mussels aligned with the results from the application of the
x
technique. As the results were statistically similar, Chatters’ increment measurement
technique was determined an accurate means for assessing seasonality.
This technique was then applied to a collection of archaeological freshwater
mussels from two rockshelter sites in northern California in order to assess the applicability
of the method on archaeological specimens, as well as to determine season of
mussel harvest and site habitation. The results further validated the accuracy of Chatters’
increment measurement technique on archaeological mussels as well as demonstrated
prehistoric mussel procurement to be almost exclusively limited to the late summer
and fall months. Season of site habitation also coincided with this data, although
additional seasons of habitation were also possible and additional faunal material must
be examined to gain a better estimation.
Through the analysis of both the modern and archaeological samples of
freshwater mussels, Chatters’ increment measurement technique was determined an accurate
and reliability means to estimate seasonality. While the technique lacks widespread
publication and adoption, it has the potential to greatly benefit both the field of
seasonality estimates and archaeology.
