Bedrock Mortars for Grinding Acorns

Yokuts woman - Tulare County - 1939 Bedrock mortar sites are also called "milling stations", and they are where long ago the Indians of California ground up acorns, which were one of the main items of their diet. The mortars they left behind are actually man-made holes, which were ground and pounded into rock slabs and boulders using stone tools called pestles. These are much like the stone mortar bowls and pestles of well-stocked kitchens. Acorns surprizingly are quite nutritious, but also horribly bitter, so much so that they must be first processed to eat. This is done by grinding the acorn meat into a mash, then pouring water through it many times to leach out the tannins that make it bitter.

Supposedly acorns from black oaks, once so processed, taste the best. This is the reason that most bedrock mortars are found where once there was a pond or stream next to a grove of black oak trees. But no one eats acorns anymore, and those who once did died off long ago, with their few survivng descendants scattered to the four corners of the compass. Yet here and there we can still find those rock slabs and boulders where they once worked, decorated with ancient mortar holes that remind us of a stone-age way of life that is no more. Below are some major bedrock mortar sites in central California that are located within a few hours drive of Solano County.

Although bedrock mortars were used by stone-age peoples in many areas of the world to prepare food, extensive use of them is limited in times past to mainly the Indians of California, the Great Basin, and the Southwest; and in particular to the Indians of California, who used them mainly to grind acorns.

The link below provides information on some archaeological sites where the Suisun and other Indians used bedrock mortars to grind acorns.







Patwin Archaeological Sites
(including Bedrock Mortar Sites)


| How Bedrock Mortars were Made | More Bedrock Mortar Sites | House Pits, Fire Rings & Groove Stones | Glossary |


The bedrock mortar sites below are organized by the native village (rancheria) that the site was probably associated with. Most sites in Suisun Valley, and to a certain extent in the adjacent foothills, were probably associated with a village near modern Rockville that early Spanish settlers called the village of the Suisun, but it was also known by the Patwin name of Yulyul. Sites in the Lagoon Valley area (Pena Adobe), to the east, likely belonged to the village of Malaca, and sites to the north likely belonged to a hill people whom the Spaniards named the Tolenas, after their village of Tolen, the exact location of which is somewhat uncertain.

A great place to see bedrock mortars in the Suisun Valley area is at Lynch Canyon County Park, which was probably the site of an ancient Patwin village that is not mentioned in any historical accounts. Here there are 70 or so bedrock mortars concentrated in a small area that is easy to hike to and open to the public. There are also nice outdoor displays of bedrock mortars that you can visit at Rush Ranch and the Pena Adobe, which also have indoor displays of artifacts. Two excellent sites that are a couple of hours drive from Suisun Valley are the Maidu Indian Museum & Historic Site in Roseville, and Indian Grinding Rock State Park near Pine Grove. Information on other bedrock mortar sites in the nearby San Francisco Bay Area can be found on the Bay Area Native Sites website.



Pena Adobe sits next to Lagoon Valley, which is a low area that once was marshland, but today has an 80-acre, man-made lake. Long ago the Southern Patwin Village of Malacca was here on the north side of the marsh, same site where the pioneer Pena family in the 1840s built an adobe using Indian labor. Today the adobe is a small museum with artifacts, and nearby are bedrock mortars to visit.



Lynch Canyon was the site of an unnamed village of the Southern Patwin people that is not mentioned in Spanish mission records, and the people here were probably listed as from the neighboring villages (rancherias) of Suisun or Suscol. Today this locality is a Solano County Park, and includes bedrock mortar sites that are reached after short hikes.



Rockville Hills was the site of a large Southern Patwin village that the Spanish called the Suisun rancheria, but the Patwins called YulYul. Here also is where in the 1860s pioneer Samuel Martin built a stone house that today is known as Stonedene mansion, and nearby is Rockville Hills County Park. Although the bedrock mortars here are closed to the public, there are still things to see in the park.



Rush Ranch is located on the edge of Suisun Marsh, and it once was a food-gathering camp of either the Suisun (Patwin) or Ompin (Coast Miwok) people. Today it is part of the Rush Ranch Open Space of the Solano Land Trust. There are bedrock mortars here that you can hike to, and a small museum with artifacts.



Tolenas Soda Springs, where it enters the Suisun plain, was at or very close to the ancient Southern Patwin village of Tolen, the exact location of which is not known with any certainty. There are several bedrock mortars here in scattered boulders. However, they are on private property that is closed to all public access.



Upper Marie Creek was the site of an ancient food-gathering camp in the mountains that was probably associated with the Southern Patwin Village of Napato (Napa). Today it is in Skyline Wilderness Park in Napa County. There are some nice bedrock mortars here, as well as a house pit and some fire rings, that require an uphill hike of about 3 miles to get to.


Upper Suisun Valley was once the site of the Southern Patwin Village of Sonetro, which was on the east side of Suisun Creek, and just a little over 4 miles north of the Village of the Suisun (also called the village of YulYul - see the Rockville Hills heading above). Sonetro was probably closely associated with YulYul, which was probably much larger. Close to Sonetro are two bedrock mortar sites, which were probably food gathering camps for the main village.



| More Bedrock Mortars | How Bedrock Mortars were Made | Glossary | Southern Sierra Pictographs & Petrolglyphs | Chumash Pictographs |








Artifacts, Tools & Baskets
of the Suisune People


Artifacts, Tools & Baskets
Arrowheads and Beads:
Shown on the immediate right are Suisun Indian arrowheads and beads that were found in middens (Indian refuse piles) located on or in the area of Bella Vista Ranch. There are also Indian burial grounds, but these are sacred and not to violated. Shown on the far right is the Patwin arrowhead collection on display at the Rush Ranch Visitor Center.
Shown above are 1) arrowheads (flat base), 2) birdpoints, 3) spear points (notched base) and two pieces of 4) knives (note the concave profile on the bottom piece). All of these are made of obsidian, probably from Glass Mountain in Napa. The white beads, also called 5) wampum, are made from clam shells, and a wide variety are found near Bella Vista Ranch. There are also two dark-gray beads made of soapstone (steatite), and some of the more uniform white beads are made of magnesite. The 6) red white-heart beads, also called Hudson Bay trade beads, are glass beads that are not made by Indians, but were made in the eastern U.S. and brought in by white traders. There are also some 7) other types of glass trade beads. The 8) clam shell pendant was not found in Suisun Valley, but is from the Santa Rosa area, and the 9) eagle claw and 10) elk tooth are modern.
Artifact Collections:
Shown on the immediate right is the Native American display case at the Rush Ranch Visitor Center. To the far right are Suisun Indian artifacts collected by local historian Rodney Rulofson Some of Rulofson's collection is displayed at the Pena Adobe.
Shown on the right are Patwin Indian baskets in the collection of the Department of Anthroplogy at the University of Calilfornia at Davis (UCD).

(photographs by UCD)

The Patwin baskets above include 1) an open-weave burden basket, 2) a coiled winnowing basket, and 3) & 4) two styles of coiled bowl baskets. Patwin baskets typically had three-rod foundations of peeled willow shoots, with horizontal coils (warps) of willow woven in a left-hand direction, and vertical weaves (wefts) of sedge root (light color), redbud (red), or charcoal-dyed bulrush (black) to make the designs.
Stone Mortar Bowls:
Shown on the right are three stone mortar bowls that were found either on, or immediately adjacent to Bella Vista Ranch. From left to right: Bella Vista Ranch, Okell Ranch and Andrino Ranch.

(photographs by Mike Clark)

Stone Tools:
Shown on the right are Suisun Indian stone tools that were found in middens (Indian refuse piles) located on or in the area of Bella Vista Ranch.
Shown above in the left-most photo are, from left to right, a digging stone or an ax, a combination grinding and pounding stone, a grinding stone (mano), and a pounding stone (pestle). The spherical stone below these tools is a cooking stone, which would be heated in the fire and then dropped into a basket filled with water to boil the water without burning the basket. Digging stones, like the one above and center, were perfectly shaped to hold in ones hand and dig a hole. They were generally more durable than the native sandstone and volcanic rock found in Suisun Valley, which means they probably came from somewhere else. This particular stone may have also been an ax. Digging sticks were pointed sticks that were sharpened by drawing the point across grooved rocks, like the one above and right from the Hume Grove site.