Geology for Archaeologists

Lithics Guide for Archaeologists

Purpose of Lithic Identification

Prehistoric Native Americans extensively utilized the Carolina Slate Belt as a source of lithic raw material. Several studies have been conducted in North Carolina related to raw material acquisition and extraction. While these studies have helped improve the knowledge concerning the archaeology of the Slate Belt, there still remain many unanswered questions and broad gaps in our understanding of this geological region as a major source of lithic raw material during prehistory.

Many questions concerning the economic importance of this area to prehistoric groups through time remain enigmatic. One of the major problems continues to be the difficulty in positively identifying the locations of specific sources from specific raw material types found on sites away from the Slate Belt. This problem is directly related to the complexity of Slate Belt geology. As a result, there exists a basic identification problem.

In general, it is the high mineralogical and structural variability of Slate Belt rocks that makes it so difficult to recognize specific source locations from specific hand specimens or artifacts. As John Davis (1992) has so eloquently stated:

"The main problem is that the basic mineralogy and geochemistry of the lithic components are similar within a range of various elemental combinations, but highly differentiated as a result of successive metamorphic and depositional episodes. The lithic components are widespread across the Slate Belt and intermixed within formations rather than localized to specific outcrops."

Most archaeologists have struggled with this problem by using macroscopic variables such as color, grain size or texture, groundmass, inclusions, and fracture quality to describe raw material types from specific archaeological sites. Others have used geologic or mineral material types such as rhyolite, dacite, argillite, or tuff for descriptive purposes. Still others default to the use of generic type names such as metavolcanic, metasedimentary, felsic, or mafic when describing the raw materials associated with specific sites. As a result, there has been very little consistency among various studies regarding the definition of raw material variability. This makes comparison and synthesis of data nearly impossible.

There is some basic nomenclature in use by geologists to describe geological samples. In order to help address this "identification problem" it is suggested that archaeologists working with Slate Belt materials adopt a basic nomenclature when describing raw material types. In essence, we all need to know a little more geology. This means archaeologists have to work more closely with geologists, with an emphasis on achieving a baseline of comparability. Macroscopic analytical techniques to define lithic raw material variation should use the same basic language adapted from geology and in consultation with professional geologists.

The Office of State Archaeology has sponsored the creation of this website to provide archaeologists with a general source of information regarding basic geology with an emphasis on Slate Belt materials. The site provides a set of methods for identifying and classifying lithic raw materials and addresses the basic levels of identification regarding various rock types. To the side one will find links to matrices that serve as guides through the Identification process. Also listed are links to a glossary with definitions of all the key terms found on the site.

Beyond identification, a major goal of the site is to further the development of a common set of terms and parameters to classify lithic raw materials. It is essential that archaeologists begin to create a more comprehensive system of this nature. Two case studies within the North Carolina Slate Belt region are provided to help illustrate an application of this system. One study is from Three Hat Mountain in Davidson County and the other is from the Uwharrie Volcanic Belt. Included in these case studies are pictures and spreadsheets outlining the details of the samples discussed.

This site assumes that the user has no formal training in geology and builds from that point. We feel this is the best and most effective approach to the issues involved. Everyone should benefit from the use of this site and gain better insight into the complexity of Slate Belt materials.

This website has been constructed as part of the 2007 Summer Internship Program coordinated by the North Carolina Youth Advocacy and Involvement Office. Kelly M. Tomlinson of the College of Charleston researched, designed, and constructed this site. Karen Browning, Webmaster of the Queen Anne's Revenge Shipwreck Project, Office of State Archaeology assisted Ms. Tomlinson in the layout and arrangement of the site. Ms. Browning is also responsible for posting and maintaining the site to the Office of State Archaeology web page. Phil Bradley, Senior Geologist with the North Carolina Geological Survey in Raleigh provided technical assistance to Ms. Tomlinson and graciously allowed the use of equipment and geologic specimens in the construction of this site. Mr. Bradley also led several specimen collection trips into the North Carolina portion of the Slate Belt. David Gunkle, Intern with the North Carolina Geological Survey, accompanied us on the collection trips and provided the GIS maps with the collection points plotted and referenced for inclusion in this site. Kelsey Zyvoloski, 2007 Intern with the Office of State Archaeology, also assisted our efforts on the collection trips. Lawrence Abbott of the Office of State Archaeology served as the supervisor for this project and provided technical assistance where needed.

Welcome to this site! We hope you find it of great interest and useful as a research tool. This site should be beneficial and provide comparative raw material data for artifacts collected at archaeological sites both within and outside the boundaries of the Slate Belt.

Please contact us with comments and feedback at lawrence.abbott@ncdcr.gov.

Lawrence Abbott,

Assistant State Archaeologist