Kumeyaay Ollas
The Wonderful World Of... Blog

The Wonderful World of Southern California Ceramics

The Wonderful World of… is a monthly blog focusing on some of the many themes, concepts, and sub-disciplines related to the fascinating world of Southern Californian archaeology.


Ceramic vessels on display at the SDAC

Throughout history, humans around the world have used clay to build shelters, hold water, store food, and even to create art – it is a durable substance still used by many cultures today. Southern California pottery and ceramic production helps archaeologists determine many factors regarding prehistoric cultures like changing technologies, trade networks, and settlement patterns. It also can be useful for dating archaeological sites. While it is still debated, ceramic production is thought to have come to San Diego around 900 CE and to the Imperial Valley around 1000 CE.

Types of Pottery in Southern California

Tizon Brown Ware sherds

There are three main types of pottery commonly found in the area: Tizon Brown Ware, Colorado (or Desert) Buff Ware, and Salton Brown Ware. Tizon Brown Ware and Colorado Buff Ware are the two types typically found in San Diego County. Tizon is common in the mountain and coastal regions while Colorado Buff Ware is formed from clays found at previous lake or river sites in Imperial County. Brown Ware is medium brown, typically with black cloudy spots created during firing. Buff Ware is lighter with a more reddish or pinkish color. Brown Ware tends to be darker in color than Buff Ware.

How Were Ceramic Vessels Used?

Ceramic vessels made great storage containers. The clay material they were made from was durable and kept pests out. They were water resistant and could help prevent evaporation. Shapes of ceramic vessels varied. Large vessels were often used for long term storage, medium for short term storage, and small (which are rarely found) were used for canteen-like purposes such as carrying water and food. The larger vessels would be hidden away in caves or buried in the ground for longer term safe keeping. Vessels used for water storage can last as cooling mechanisms for about two years; then salts begin to penetrate the clay, and they no longer efficiently cool the water. The same clay was also used to make beads, pipes, and pendants, and these items are helpful in understanding past trade and settlement patterns.

How Were Ceramic Vessels Created?

Black clouding created during the firing process

Often, the clay that is used in the creation of ceramic vessels is composed of silica, water, and alumina. When the clay is wet, it is moldable and can be used to form the vessel into a desired shape. When extreme heat is added during the firing process, the clay hardens as the water evaporates from the composition. The Kumeyaay tradition of clay production and techniques was passed down from mother to daughter. Clay source locations were kept secret.

Sherd with basket impression

One of the more common techniques used in ceramic vessel creation in Southern California was the paddle and anvil technique. Beginning with the bottom, an older vessel or basket would serve as the mold and a rock or clay anvil, was used to press the outside until the desired shape was achieved. The potter’s wheel was not used in North America so these resources were made by hand. When looking closely, many times these ceramics contain evidence of basket impressions and fingerprints.


Sherds, or ceramic vessel fragments, are found all over Southern California sites, and the San Diego Archaeological Center has an abundance of these important pieces in permanent collections. The most frequently found pottery objects are sherds. Although clay is a durable material, over time (and after being buried in the ground) vessels break. Whole vessels, referred to by the Kumeyaay as aas’kay in Ipai and saa’kay in Tipai and also referred to as Ollas (the Spanish word), are utilitarian vessels used for a variety of purposes, like food and water storage, or for keeping personal items.

Different types of fragments, such as a rim sherd, can be diagnostic for archaeologists. Ceramic sherds can determine the vessel’s original size or shape. A rim sherd can indicate a specific style or more specifically point to a period dependent upon when the style was being used by a culture. Therefore, a rim can tell us more than just a plain sherd.

Repairing Ceramics

Ceramic vessels were highly valued by their owners, and if they were to break, there were many repair techniques that could be used. Lacing was a common repair technique, where cracks in vessels are repaired by drilling small holes on either side of the crack and then lacing together yucca (plant) fiber or sinew (animal tendons) to cover it. If a vessel was broken beyond repair, many times it would used for another purpose. For example, a broken water vessel that no longer used to hold water could be made into a bowl or pot for cooking.

Field Trip to the Imperial Valley Desert Museum

Credit: Imperial Valley Desert Museum

I recently had the opportunity to meet with Curator Kristin O’Lear and Executive Director Dr. David Breeckner for the Imperial Valley Desert Museum in Ocotillo, California, where they preserve and protect an incredible array of ceramic vessels. In the Spring of 2015, the Museum’s permanent collection of vessels, or ollas, went on display. This excellent display highlights the different sizes, shapes, and types of vessels found in the area. Many of them show original repair work, and because they preserve quite a few complete vessels, you really get a more detailed picture of how these incredible cultural resources were used.

Credit: Imperial Valley Desert Museum

The type of vessels that really stood out to me was referred to as a two-neck or Wedding Olla. At the Center, we do not have any vessels that look like this. A two-neck olla is referred to as the Wedding Olla because the two necks represent the union of two people. After Southern California had been colonized, Indigenous cultures began selling ceramic pottery as tourist art. The two-neck olla production increased in the early 1900s once they become popular with tourists.

by Jessica McPheters, Collections Manager

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.