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| Bedrock Mortars on a bench above the South Yuba River |
Bedrock mortars are anthropogenic circular depressions in a rock outcrop or a large boulder or slab, used by people in the past for the processing of acorns, seeds and other food products. There are often a cluster of mortars in proximity indicating that people gathered in groups. Mortars are used in conjunction with pestles with a variety of shapes, often with modified surfaces, for other food preparation and ceremonial functions. Pestles, because of their size and/or graceful shapes, are often removed from the site by collectors. Bedrock mortars are the most prevalent artifacts (or archaeological features) found in California from the east side of the Sierra Nevada to the Pacific coast. Even though they exist in many other parts of the world California, by far, has the greatest density.
They are reminders of the peripatetic, yet focused, hunters, fishermen, plant gatherers and herbalists who skillfully managed these lands for thousands of years. Originally, indigenous people were focused on big game hunting but over the centuries shifted to a reliance on botanical foods. Their descendants are still here. The people who made the bedrock mortars are called hunters and gatherers, but that’s a woefully inadequate description for a range of activities that encompassed efficiency and a deep understanding of ecology blended with practical, social, spiritual and aesthetic dimensions.
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| Cut-Eye Fosters Bar. North Yuba River |
Bedrock mortars are generally associated with the settlements and camps of indigenous peoples, but here in the Sierra Nevada foothills they appear at various elevations and in different ecosystems, from meadows with springs to ridgetops with wetlands, near creeks and rivers, on flatlands and slopes and in many other settings. They also can be isolated or scattered in “neighborhoods” along a creek or in a shallow valley. Outcroppings and boulders usually contain from one to twenty mortars and sometimes more. “Tco’Se”, a former Miwok settlement, also known as “Chaw Se”, or “Indian Grinding Rock State Park”, near the town of Volcano in Amador County, California, has an outcropping with over 1,000 mortars.
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| Dry Creek, a tributary of Bear River |
Although they are most often associated with acorn pounding they were not limited to that function. Early and modern ethnographers, as well as those who used them, acknowledge the use of mortars to process nuts, roots, berries, herbs, medicinal plants, fungi, insects, small animals, rodent and fish bones for soups, for softening dried fish and meats, as well as for paints, pigments and substances used in ceremonial contexts. Shallow mortars may represent multifunctional tools and workstations for tasks other than acorn processing.
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| Fragments of a milling slab, or "metate", used for milling or grinding small seeds. Round Mountain, South Yuba. |
Sugar pine nuts in sub alpine forests and gray pine nuts in lower elevation rolling hills are other desirable foods. There are hundreds of bedrock mortars in sugar pine habitat within the Yuba River watershed. Nut hunters would often camp at a favorable elevation then search for the most productive trees. Archaeologist David Hunt applied GPS data and statistical analysis to the location of Nisenan and Washoe campsites in the watersheds of the Middle and South Forks of the American River and determined that sugar pine nuts were collected at many locations and processed at numerous small bedrock mortar locations. In his opinion sugar pines probably extended farther westward than they do now. |
Archaeologists refer to bedrock mortars as “BRMs” and estimate that they were widely used in the Sierra Nevada appearing about 1,300 years before the present era (BPE), and that this adaptation was coincident with the arrival of the bow and arrow. Since there is no way to accurately date BRMs archaeologists used associated artifacts such as projectile points with distinctive shapes and created a typology based on radiocarbon and obsidian hydration dating of artifacts from key regional sites. This is less than ideal because the stone tools may have been left before or after the BRMs were in use. There is no direct correlation.
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| Bedrock mortars at Starvation Bar on the South Yuba River |
In the early 1960s California archaeologists hypothesized there might be a relationship between mortar size (as measured in volume) and population size and/or duration of occupation of the site. They theorized that the amount of stone removed from the grinding process is important. If a volume change rate per unit of meal created in the mortars could be found it could provide insight into the amount of food consumed in a specific time period. Other archaeologists followed, testing similar research designs. Eventually the California Office of Historic Preservation developed a new series of archaeological site recording forms, including one specifically designed for recording attributes of bedrock milling features. In time this focus began to shed light on women’s activities and suggested that they had more authoritative control than was represented in many of the ethnographic accounts collected by male anthropologists.
When BRMs were found between 6,500’ and 7,500’ within what is now Yosemite National Park archaeologists surmised that either lots of people gathered for a relatively short time span to process acorns or fewer people habitually reused the same bedrock mortars. They asked, what prompted the change from “portable” mortars to bedrock mortars? Since portable mortars are, despite the name, way too heavy to transport, I think the answer seems obvious.
An influential 1985 study of bedrock mortars at Crane Valley, divided mortars into three classes according to their depth. Depth followed function, according to the contemporary indigenous Western Mono people. The Crane Valley study determined that to render hulled and peeled acorns into a useable flour, or meal, shallow “starter” mortars, less than 2.2” deep, were used, followed by pounding in medium depth “finishing” mortars, between 2.2” and 3.75” deep. Mortars deeper than finishing mortars enabled the processing of hard seeds. It’s a valuable study, providing considerable insight, but the quantitative approach to mortar typology is highly reductive. Crane Valley is hundreds of miles south of the Yuba River, where I’m writing from.
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| Foothill Women Pounding at a Bedrock Mortar |
The Nisenan, Koncow, Northeastern Maidu and Washoe people of the Yuba River watershed were mobile for most of the year following the patterned ripening of plants and the movements of animals and fish within two to three ecosystems. They participated in ecological processes and influenced outcomes by the judicious use of burning as a tool. They also adjusted visits to seasonally accessible camps based on available resources such as food, medicine, basketry materials, flicker feathers, woodpecker scalps, etc., to coincide with trade opportunities, the ceremonial cycle, socio-political necessities and visiting. Two Nisenan events, similar to what westerners call holidays, were Weda, or the first flower ceremony, signaling spring and the splendor of nature’s fecundity. And in the fall was the Big Cry, when the dead were honored, and it was also the time for acorn gathering. Both of these events and others featured feasting, singing, dancing, gambling and socializing.
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| Julia Parker Winnowing Acorns |
Lizzie Enos, a Nisenan woman who preserved Nisenan knowledge and skills into the 1960s had this to say about Weda, “From all over they come, and when that dance end, maybe it was here or down in Auburn, then pretty soon they have another one up there at Colfax. Then from there, oh maybe next ten days. They have another Flower Dance over to Grass Valley and Nevada City. Every camp have to have that Flower Dance in spring.” Her comments show that Nisenan culture was very much alive in the 20th century (Enos was born in 1881) and her rendition gives a positive feeling of jubilation and cultural revitalization. Moving from place to place was part of the fluidity and resiliency that characterized Nisenan lifeways and was not perceived as drudgery.
Two common misunderstandings about bedrock mortars have been hanging around for many years. Many observers speculate that mortars deepened though wear; that they deepened as a result of pestles striking their bottoms. This notion holds that the deeper the mortar the older it is. The Crane Valley study, and other sources, demonstrated that this is not true. There is a second, and even more prevalent, misconception that mortars are grinding holes. Native women use bedrock mortars to pulverize shelled and hulled acorns by pounding and not grinding. There is always a layer of acorn meal between the pestle and the interior of the mortar. Acorn pounding is a skill with very high standards and any rock chips or grit in the finished product is not acceptable. The demonstrations of Lizzie Enos and Julia Parker, indigenous cultural interpreters, exemplified this detail.
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| Lizzie Enos Pounding Acorn Meal Photo Courtesy of Richard Simpson |
Archaeology is conducted within theoretical constructs and insists on its scientific validity by heaps of measurements and statistical analysis. As computer-generated site recordation forms evolved, they have become more data-intensive at the expense of the flavor and feeling of a locale and its constituents. Even determining site boundaries has become more problematic because of modifications in the historic era. Concerns about property ownership and “cultural resource management” considerations can hinder the designation of a site as an agglomeration of neighborhoods (or loci within a large site) because there is a tendency to create separate sites for ease of management. Many technological advances are valuable, but humans of both the past and the present can be unpredictable, endlessly creative and sometimes tricksters. It’s difficult to keep an open mind in a sea of conveniences.
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| Mortars on a Tributary of Rock Creek/South Yuba River |
The appeal and usefulness of the scientific method is in its continual theorizing, testing of hypotheses, comparisons and an extreme reluctance to arrive at conclusions (especially in archaeology, which in my opinion, straddles social science and humanities). This isn’t necessarily a problem because concluding or “knowing” tends to close the discussion. It’s important to feel uneasy with conclusions because the search for knowledge is an ongoing process. In Ursula LeGuin’s, Four Ways to Forgiveness, she concludes that “All knowledge is local. All knowledge is partial.”
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| Bedrock Mortars in the Lower Foothills Near Dry Creek/Bear River |
In the latter half of the 19th century many bedrock mortars were impacted by ferocious bouts of placer gold mining that was prominent in Yuba River country. There is still gold, and its allure remains a threat today, but try to imagine how many bedrock mortars were destroyed, tumbled over, re-located, inundated and buried? I worked as a field archaeologist and historian in this region for over twenty years and I remain a curious rambler, so I have seen hundreds, if not thousands of bedrock mortars. Often, they are all that remains of an aboriginal campsite or settlement – the remnants of an archaeological site that has returned to the earth, or a place that has been destroyed, or looted.
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| Appropriating Bedrock Mortars at Sweetland Creek/Middle Yuba River |
My response to bedrock mortars and their settings has always been more visceral than scientific. I find them sculpturally simple but complex, both metaphorical and literal, stark (but formerly lively) and enduring forever, at least in human terms. The bedrock mortar’s place in space is persistent, but dynamic because soil-creep, mass-wasting, duff accumulation, alluvial deposits, erosion and other natural processes have covered many outcrops. In time, many of them are folded back into the earth and become invisible. Are they then gone? A place where young children hovered around their mothers, where women pounded foods and medicines while joking, gossiping, sharing skills, ideas and songs? How will sub-surface bedrock mortars affect behavior on the newly formed surface fifty or a hundred, or thousands of years hence? Will the place have a certain “vibe?” Why do some places have a special or “magical” feel about them?
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| Bedrock Mortars on the South Yuba River/ Canyon Creek |
Americans have grandiose notions and specific ideas about monuments. Examples include Mount Rushmore, Maya Lin’s Viet Nam Memorial and the toponym that designates a unique geological feature in the Sacramento Valley of California as the “Sutter Buttes.” Today, California’s bedrock mortars serve as diffuse cultural “monuments” or touchstones, if you will, that honor and promote reflection on the unique and effective practice of hunting and gathering, and women’s important role in that process for centuries to come.
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