Mystery Walls of the East Bay

Apr 16
10 min read

MYSTERY WALLS OF THE EAST BAY:

Mission Peak Regional Preserve

Part I

History

On the east side of San Francisco Bay, thousands of people travel on Highway 680 between Milpitas and Fremont. Stuck in traffic, a few might notice a dark streak high on a ridge, and assume it’s just another outcrop in a rocky hillside. It’s not. It’s one fragment in the Great Mystery of the Bay Area--the Walls on the Mountains.

No one knows who built them, or why. They follow no obvious pattern and enclose nothing, ending abruptly in one place and reappearing as suddenly in another. They once extended along ridge tops from Milpitas to Berkeley.

In 1904 (August 14 and September 4) articles by Dr. Henry Meyers in the San Francisco Chronicle stated the walls had once extended over five miles along the ridge tops of the “Contra Costa Hills” (now the Berkley Hills). The average height was two to four feet, and certain base stones weighed over one-quarter ton. For over one and one-half miles, the walls ran unbroken over the crest of “Old Baldy” (now Vollmer Peak in Tilden Regional Park). Artifacts in stone and clay were found buried near the walls or stashed in small volcanic caves.

An article by Harold French in the Oakland Tribune (15 October, 1916) quoted older residents who stated the walls had been intact as early as the 1860s.

Decades of urbanization and vandalism have left only fragments. The most extensive and best preserved on publicly accessible land survive in the central Diablo Range, in a regional preserve called Mission Peak.

180 miles long and twenty miles at its widest point, the Diablo Range extends from the Carquinez Strait in the North Bay Delta to the Antelope Valley in Kern County. The highest elevations—all visible from Mission Peak—are San Benito Mountain (5,240), Mt. Hamilton (4,265) and Mt. Diablo (3,849).

Through passes and trails in the Diablo Range, an ancient and complex trade network linked Bay Area and Coastal Ohlone, Miwoks in the Delta and Northern Yokuts from the San Joaquin Valley with Native Americans in the Sierra Nevada, Southern California and beyond. Goods included obsidian, acorns, sea shells, salt, pine nuts, seeds and animal skins. Red cinnabar ore from the New Almaden mines near San Jose has been found at the mouth of Oregon’s Columbia River.

Ohlone families harvested acorns from the same territories and even the same oak groves for generations. Using stone pestles on bedrock or free-standing rocks, women pounded the acorns into flour, leaving round “mortar holes,” as well as less obvious flat depressions where other plants and seeds were ground and scraped.

Part II

The Walls: Mission Peak to Monument Peak

The walls are dry-laid, averaging one to three feet wide and two to six feet high. Some walls run for hundreds of feet, connecting large outcrops of natural stone. “Ghost Walls” are fragments; scattered piles or lines of stones lost in the grass. In some sections, gaps in the earth left by erosion reveal layers of stone beneath the exposed walls.

No wall has been found below 1,700 feet.

Rough stones might have been obtained from large outcrops of rock. But no quarries have been found, and because the walls are often located in areas without outcrops, even the smaller stones may have been transported from a distance.

An historian suggested that the walls near Monument Peak had been constructed on a seasonal basis by an Amish farm family who also ran a blacksmith business. (1).

Segments with more conventional construction may indeed have been built by pioneers. However, the extent of the walls, their size and location precludes construction by a single family. Often stacked on or linked to natural outcrops, many stones are too large to carry. Lifting some of the base stones would require a block-and-tackle; draft animals to pull wagons, and hundreds of people working for decades in the sun with no shade and no easy source of water. There are no enclosed spaces, nothing that might have been a room or a corral. Short “fragments,” some less than less than two feet high on steep slopes are neither practical, nor functional.

Many walls have stones covered with lichens, which grow at a regular rate. Calculating the lichen’s age might provide an estimate of when the walls were built. Another method would involve complex calculations about the length of time it would take one person or a group to quarry and stack ‘x’ number of stones, and how much water and food one person required per day multiplied by heavy labor.

Some of the rock walls on the [McClure/Peak Meadow] ranch were so old that when a biologist friend came to visit in the 1950s, he indicated that some of the lichens growing on the rocks were over a thousand years old. Unfortunately, the walls he looked at have been torn apart by hikers during the past 25 years. (Activities at Peak Meadow, Peak Meadow Ranch: Adminpilot, adminpilots.3.amazonaws.com)

Occasionally oak and other trees have grown, died and decayed between the rocks, displacing parts of walls. In the mid 1980s, a forestry professor from UC Berkeley was persuaded by a local wall devotee to test a core sample from one of these trees. While the sample indicated that the tree [when it was cut down] was at least 130 years old the core had already disintegrated, so the test was largely inconclusive. (Rock Walls of Mission Peak Regional reserve: An Overview. Sponsored by the East Bay Regional Park District and the Americorps/East Bay Conservation Corps. Courtney Norris and Terry Buxton. August 17, 1995).

The report does not specify the location of the tree. However, in the Calaveras Valley, on private ranch land accessible only with the owner’s permission—but visible from park trails—there is a straight wall over 3,000 feet long. Near a gap where stones have been removed, the wall is gripped by old roots from a weathered tree stump.

Early Spanish and Mexican settlers questioned local Ohlone Indians about the origin of the walls. According to Harold French in the Oakland Tribune (15 October 1916) “There was a tradition among the Matalanes [The Matalan were an Ohlone tribe in what is now Santa Clara County]…that the walls were fortifications built by the ‘hill people’ with whom they warred.”

However, pre-colonial Ohlone did not build out of stone. In the valleys and along the coast, primary building materials were tule grass, willow branches and redwood bark. In the mountains, trees branches and thatch made of bundled grass. Lacking domestic animals, Ohlone had no reason to fence pastures or build corrals. And because they did not engage in mass organized warfare, they had no need to build defensive walls.

Although walls would have been on land owned by the Spanish colonial ranchos of Los Tularcitos and Agua Caliente, 19th-century legal records involving disputes between the ranchos and the U.S. government do not mention stone walls, which would have been convenient landmarks.

Colonial Spanish and Mexican settlers usually built stockades out of logs, fences out of willow and brush, and buildings out of wood and adobe. Stone structures were not common.

Except during round-ups, rancho and mission livestock ran wild. Logically, it would make sense to build corrals near settlements. Linear stone walls in the back country—accessible even now only through a difficult and exhausting hike—would have been useless.

One theory suggests the walls were built by Ohlone slaves. But the Spaniards, practical and supremely confident, had no hesitation about revealing in detail their often brutal treatment of Native Americans. If the Spaniards used slave labor to build the walls--a massive project that would have taken years, perhaps generations--it is inconceivable that the work would not have been mentioned in contemporary diaries, letters, military reports, mission records--or that it did not survive as oral history among the Ohlone, who out-numbered the Spaniards. Slave laborers, with rocks and tools already in their hands, could have attacked and overwhelmed their guards before escaping into the mountains.

Ohlone worked primarily for the missions and ranchos, not the military government. The Church and the military were constantly at odds over politics and social policy. Any attempt by the military to conscript laborers away from their agricultural duties to build walls for no logical reason would probably have been met with fierce resistance by religious authorities, the battle preserved in official documents from both sides.

In 1860, Jose Romero (born in San Jose in 1800) testified in a private land grant case that Monument Peak had been known as Cerro de las Calaveras; Hill of the Skulls, so named “...because when it was discovered by the first inhabitants it was recognized and known as a place where the Indians used to worship and where they kept their idols. Some remains of idols were found there.” (2).

PART III:

The Hike

It begins either in Fremont at the end of Stanford Avenue in a small parking lot surrounded by pseudo-Mediterranean McMansions, or in Milpitas at the Sandy Wool Lake parking lot in Ed Levin Park.

The distance between Stanford Avenue and Monument Peak—with the most extensive system of “long walls”—on the Alameda-Santa Clara County line is 4.44 miles. The distance between Ed Levin Park and Monument Peak: 3.3 miles. The entire one-way hike, starting at either Stanford Avenue or Ed Levin Park, is 7.74 miles.

Walls adjacent to the trails are easy to see. However, prior to the introduction of Google Earth in 2001, walls off the main trails could only be found by chance and extensive hiking.

Google Earth, making it possible to explore in minutes what would have taken days on foot, reveals the wall’s true extent and complexity. While Google Earth provides distance, perspective and patterns, it also has a major flaw. Zooming in too closely—usually below 500 feet—images become distorted, so it’s not aways possible to know for certain if linear features are human-made walls, modern wood fence lines, natural outcrops, cattle trails or earth fissures.

Google Maps incorporates images from hikers documenting the Bay Area Ridge Trail and the Peak Trail between the Stanford Avenue trailhead and Ed Levin Park—an area which includes walls between Mount Allison and Monument Peak. Unfortunately, many sections with the most extensive walls are not included. The virtual hikes also have another problem: it’s not possible to leave a trail and explore.

The Preserve is officially open between 6: 30 a.m. and 9 p.m.. Around sunset, it’s common to see people heading up to the high country to stargaze, pray, meditate, play music, or begin the 28-mile “dry camp” hike along the Ohlone Wilderness Trail to Lake Del Valle.

Leaving the parking lot, past the bulletin board covered with notices about guided hikes, park facilities, warnings about rattlesnakes, feral pigs, mountain lions, and the need to stay hydrated, hikers follow the Ohlone Wilderness/ Mission Peak Trail across a wide field; a gradual ascent that suddenly becomes one of the steepest and most rigorous hikes in the East Bay.

From the parking lot (elevation 380’) it’s 2.34 miles to the junction of the Peak Meadows Trail with the Ohlone Wilderness/ Mission Peak Trail which becomes the Regional Park Trail. (The only way to know for certain where trail names change is by taking an aerial hike on Google maps). The elevation: 1,980 for an elevation gain of 750’.

People exploring the walls keep left, following The Regional Park Trail is bisected by an east-west wall extending 0.3 mile to the Wings of Rogallo’s launch site for advanced-and intermediate-rated hang-gliding and para-gliding pilots. The association is the only civilian group allowed to drive on the reserve, and the site is only accessible with a park permit and four-wheel drive.

The wall’s lower section is a natural place to sit and rest, have a snack, water, and contemplate the view. It’s also the first place a lone hiker might perceive how isolated they are in a world where the only sounds are the wind hissing, rustling and rattling through sparse grass and dry weeds; the hunting cry of hawks, and the scratch of lizard claws on stone. The hiker might see a bullsnake (and, if fortunate, no rattlesnakes) slithering over the wall and down into the grass. The only birds the hiker is likely to see in the open are tiny grey Rock Wrens that cling and climb like lizards, using gaps in the walls as nesting sites.

Below Mission Peak, the Regional Park Trail intersects with a road leading to buildings on the McClure/Peak Meadow Ranch property. The main house was built in 1855 by Thomas Millard (1820-1916), a Gold Rush pioneer born in England. In 1921, Albert Alfonso Moore purchased the property. In 1928, after his youngest daughter, Margaret Moore McClure (1891-1982) inherited the property, the home was extensively remodeled. The original barn became a residence with a bath and three bedrooms. After McClure’s death in 1982, the family donated the property to the East Bay Regional Park Service.

On the road to the McClure house, there is a large natural rock pile linking two walls; one section approximately 650’ long and the other, approximately 550’ long, connecting to another natural outcrop. Their location on a bluff overlooking the Bay Area,, and noting that from below, the wall is almost invulnerable to surprise attack, a hiker might have an unexpected thought, It’s a sentinel wall. They were afraid of something.

On the north end, the wall is built into the angle of large boulders. On the inside, ground into the flat side of a natural rock, there are small circular “cupule” petroglyphs and a hole, possibly for grinding acorns, over eighteen inches across and almost a foot deep.

On a pile of large boulders covered in lichens, deeply incised ovals about four inches apart, and a shape like a double club at least eighteen inches long do not appear to be natural.

Hikers looking for the walls follow the treeless Eagle Trail and Bay Ridge Trail behind Mission Peak: an easy hike 1.1 mile hike to Mount Allison between hills covered with small scattered stones, single boulders and large outcrops: visible bones of the converging Hayward, Calaveras, Mission and Warm Springs earthquake faults.

On the east, the land drops away into the Calaveras Valley, then crosses over forty miles of the rugged, sparsely populated Sunol/Ohlone Wilderness until it reaches Interstate 5. Place names tell the stories: Mt. Misery, Sulphur Gulch, The Devil’s Hole, the Devil’s Pit, Hideout Canyon, Poverty Ridge, the Burnt Hills, Murderer’s Gulch.

Park Ranger looking over a wall at the Sunol/Ohlone Wilderness. (Author’s Photo).

The Sunol/Ohlone wilderness seen from Monument Peak. (Google maps).

In just 0.6 miles between the Alameda/ Santa Clara county line and the junction with the Sierra Trail, the road is bisected four times by the most extensive, almost unbroken, single wall (its entirety visible only on Google Earth) with an estimated length of 2,400 feet.

Here the walls and the hike end. No walls have been found between the last junction and Ed Levin Park. On the long walk back to the Stanford Avenue trailhead, the hiker—noticing that the outcrop they’d passed on their way to Monument Peak is actually a wall—might think And there’s another over there…how could I have missed them?