Dig Deeper Blog,  Exhibits

Dig Deeper: What Are All of These Stone Chips?

Dig Deeper is a monthly blog focusing on the basics of archaeology by taking a closer look at the exhibition Archaeology 101, which is currently featured at the Center.


Now that we have discussed the different types and uses of stone tools and know how they were made, let’s dig deeper and learn about the waste left behind after a stone tool was created.

What is Debitage?

Debitage dated to the San Dieguito Complex (10,000-7,500 BP)

The prehistoric sites in San Diego County often contain many stone chips and flakes that are discarded during the production of stone tools. What are all of these stone chips? These chips and flakes are generally referred to as debitage. Debitage can be defined as the waste that is chipped away from the stone while making a tool. This includes flakes, shatter, and even dust created during the flintknapping process. In addition to the many stone tools preserved at the SDAC, the Center also collects and preserves debitage.

What Can Archaeologists Learn from Debitage?

Why would we want to preserve and collect discarded waste if it wasn’t “used” by its creator? When archaeologists are excavating a site, they may find debitage even if the tool created is nowhere in sight. Even if the tool is not found during a dig, debitage can tell archaeologists a lot about the tool, including where the stone originally came from. It also indicates important information about the people who created the tools.

By examining debitage, archaeologists learn a lot about the site. The size and type of the debitage may indicate the method that was used to produce the tool. An analysis of the type of stone used can give clues to who made the stone tool and when. Even the smallest chip can tell us where the original stone came from.

An obsidian point found at a site in Carlsbad

Obsidian is a great material for making chipped stone tools. It is a natural glass produced by the rapid cooling of molten rock. There is no source of obsidian found in San Diego County, yet many sites are littered with obsidian flakes, tools, and debitage. What does this tell us? This type of debitage, stone tool present or not, indicates that there was long distance trade happening in the area. Obsidian found in San Diego County is usually sourced from Obsidian Butte near the Salton Sea in Calipatria, Coso Range near the Nevada border west of Death Valley, and Baja California.

Relative Dating with Debitage

As we discussed last month, tool making changed with time and so did the materials that were used to produce them. If a tool is not present a site, but debitage was left behind, an archaeologist has a better chance at dating the production of the stone by analyzing the debitage and determining the type of stone. In San Diego County, these types of stone were generally tied to the dates associated with them:

  • fine-grained Santiago Peak Volcanics and the Paleoindian/San Dieguito (10500 BP – 7200 BP)
  • coarse-grained cobble Volcanics and Quartzites and the Early Archaic/La Jolla (7200 BP – 4000 BP)
  • Quartz, Chert and Obsidian and the Late Archaic/La Jolla (4000 BP – 1300 BP)
  • an increase in Quartz (at least 15%) in the Late Prehistoric (1300 BP – 1000BP)


It’s safe to say that debitage plays an important role in archaeology. Collections curated at the Center may have thousands of pieces of debitage in them. These artifacts are treated the same as stone tools, carefully counted,  weighed, and preserved for research conducted now and in generations to come.

Up Next

We have learned about some techniques used to date sites and artifacts but is there a way to know definitively when something was made?  Come back next month to dig even deeper and learn about absolute dating!

By Jessica McPheters, Collections Manager

Learn More

Archaeology 101 Exhibit

Artifact of the Week: Debitage

Volunteers work in the Center’s Research Library, cataloguing materials and organizing on a computer-based system.

Marketing and Administrative Volunteers assist the Development Office or Administration Office with data entry, updating marketing materials and clerical tasks. Computer experience is a plus.

Docents welcome visitors and answer general questions regarding the Center and exhibits. Docents staff the gift shop and help out with administrative and curatorial tasks.

Volunteers support event activities at the Center, such as the Annual BBQ, lectures, workshops, and fundraising events. Be a part of the party!

Volunteer provide support for K-12 programs offered at the Center. These are fun, hands-on programs that kids really enjoy. Teaching experience is a plus, but not required. Background checks are required.


With the assistance of Center staff, the intern will use photogrammetry to prepare one or more archaeological collections for digital preservation, as well as create a virtual museum exhibit for our Public Archaeology department. Per approval, special projects of the intern’s choosing are also available. During the research and planning, the intern will receive guidance as appropriate to their selected project. Prospective interns should already be familiar with photogrammetric procedures, and Agisoft Metashape.

Collections Management

With the assistance of Center staff, the intern will prepare one or more archaeological collections for curation. During the course of the internship, the intern will learn to identify artifacts and ecofacts common to the San Diego region, including lithics, ceramics, historical objects, and faunal, botanical, and mineral specimens. Center staff will instruct the intern on archaeological laboratory procedures such as basic artifact analysis, manual and computer cataloguing, storage requirements, and preventative conservation. In addition, the intern will become familiar with historical trends in archaeological practice in the San Diego area and will be introduced to current legal and ethical issues in archaeological curation as well as the concerns and rights of culturally affiliated groups with regard to archaeological materials.

Development and Marketing

Under the direction of Center staff, the intern will support the department in various activities, including, but not limited to, fundraising and grant research; e-newsletter development; social media marketing; and website maintenance. This internship will give the intern valuable, real-world experience in non-profit fundraising and marketing.

Geographical Information Systems in Archaeology

Prospective Interns must have completed three courses: Introduction to GIS, GIS Database Management, and Intermediate/Advanced Methods in GIS. The intern will be assigned a project where they will create shapefiles and maps for curated archaeological collections, museum exhibits, and/or public outreach using ArcGIS 10.6. Center staff will instruct the intern on archaeological GIS laboratory procedures such as computer cataloguing, storage requirements, and database management.

Library Science

With the assistance of Center staff, the intern will arrange and catalog materials in the Center’s library. During the course of the internship, the intern will take a leading role in the cataloging, sorting and storing of research files and creating user guides for these collections. Center staff will instruct the intern on archival procedures, computer cataloging, storage requirements, and preventative conservation.

Public Archaeology

Harness your passion for Public Archaeology and gain hands-on experience with K-12 museum field trips, lectures, and public outreach. Additional projects may include creating virtual museum exhibits and activities, assisting in the development and implementation of K-12 curricula programs, planning and presenting public facing content, or educational field trip content of your own design. Must be able to pass a Live Scan.