Harper Flats grinding holes, where Native Americans prepared their food.

This hike takes you up Pinyon Wash, lined with wildflowers in the spring, and into Harper Flat, an extensive area of Native American use. At the end of Pinyon Wash Road, the well-marked trail takes you through a stand of imposing boulders. After some rugged ups and downs over the rocks, you land in a mostly smooth, sandy streambed, gradually angling up-hill. If it’s April and the rains have come, you’re in for a colorful treat. Clumps of brilliant yellow brittlebush and rivers of golden poppies spill down the boulder-strewn hillsides, as prickly teddy bear chollas raise their furry arms. Silver chollas make their stand in the small pale blue seas of color formed by common phacelia. Watch your step so you don’t trample the desert stars, small white flowers with yellow centers that huddle low, barely raising their heads above the ground.

After about a mile, the wash opens up into a large flat area. Scanning Harper Flat, conspicuous plants are creosote bush and ocotillo. Ocotillos reach multiple long, spiny arms toward the sky. If it has rained recently, each branch will be tipped with brilliant red flowers. Creosote bushes are mounded plants waist to head high characterized by tiny deep-green leaves, open branching structure, and tiny yellow flowers in the spring. Scientists credit an ancient creosote bush as the oldest living plant in the world. Both hillsides and the flat are dotted with the gray-green rosettes and tall flower stalks of the desert agave. Each spring Native Americans came from all around to harvest the newly sprouting flower stalks of agaves that were baked in pits to make a sweet treat.

Turn left along the hillside and start looking for multiple bedrock mortars worn into the boulders. Native peoples used these grinding holes in the preparation of food. As you wander and search along the edge of the hillside, also keep an eye out for broken shards of pottery and obsidian flakings left from the making of arrow points or other tools. Look, but do not collect, and if you pick up anything, be careful to return it to the same place and position. This is important to archaeologists who record these sites. All antiquities are protected by law and may not be removed.

In addition to native artifacts, watch for the magenta blooms of beavertail cactus and the creamy blossoms of fishhook cactus hiding away under bushes. If you’re lucky you may spot a banded rock lizard, with a black collar on its neck and a banded tail. These agile lizards live on large boulders where they escape predators by running up vertical rock faces or skittering around to the opposite side of the rock to hide.

After about a half a mile, you will reach two large rocks, maybe 15 feet high. The sheltered space between them is a fine place to relax and have a snack among the Native American grinding holes before tracing your steps back to your vehicle. Keep your eyes open for treasures and pleasures you missed on the way in.

Distance from downtown San Diego: 83 miles. Allow 2 hours’ driving time; 4WD recommended. (Anza-Borrego Desert State Park) From Julian, drive east past the junction of Hwy 78 and S3/Yaqui Pass Road (Tamarisk Grove intersection) for 4.1 miles, then right into Pinyon Wash. Go 1.6 miles, take the left fork to Pinyon Wash, and drive 3.3 miles to the end of the road.

Hiking length: 3 miles round trip

Difficulty: Moderate to moderately strenuous; Elevation change up to 500 feet

*Canyoneers are San Diego Natural History Museum volunteers trained to lead interpretive nature walks that teach appreciation for the great outdoors. For a schedule of free public hikes: http://www.sdnhm.org/canyoneers/index.html