Saving Natural Lands, Now and Forever

Connecting the dots

Hikers' field trip into McKenzie Preserve not only delves into nature's
intricacies but also the role humans have played historically.

By Marek Warszawski / The Fresno Bee

(Updated Wednesday, March 1, 2006, 9:28 AM)

The dead pine standing 20 feet off the trail looks like an
 ordinary tree, only peppered with small circular holes.

Not to Rodney Olsen. While others see only a dead tree,
 Olsen sees a food bank, one critical to the survival of
 several species of birds inhabiting McKenzie Preserve.

"It's called a granary tree," the biologist says. "At one
time, each of those holes contained an acorn."

Olsen explains that the holes were created by a family of acorn woodpeckers using their short, pointed beaks. Other birds, many lacking the

ability to excavate wood, not only eat the acorns but also nest in the vacant holes.

Turns out the ordinary looking dead tree isn't just a food bank but an apartment building as well.

Such are the complexities of nature. Often, it takes an expert to interpret them.

That's what made Sunday's field trip sponsored by the San Joaquin River Parkway and Conservation Trust such a treat.

Besides Olsen, our group of 30 hikers is accompanied by geologist Craig Poole and archeologist John Pryor. Poole and Olsen are Fresno City College instructors; Pryor is a professor at Fresno State.

"What we're trying to convey here is that it's all connected," Olsen says.

The McKenzie Preserve is an undeveloped 2,960-acre parcel located on the north side of Auberry Road between Friant and Prather. Owned by the Sierra Foothill Conservancy, a nonprofit land trust, the preserve contains blue oak woodlands, chaparral and volcanic tabletop mesas rising 1,000 feet above the valley floor.

The area also has an interesting human history.

The Yocut tribe used to dwell here, as did gold miners. Bisecting the property is the old SJ&E railroad grade, which was used to construct the Big Creek Hydroelectric Project.

The first thing you notice about the McKenzie Preserve is how green everything is. However, that's not the way nature intended.

Poole explains that 99% of the grasses are non-native. They are European species, brought to this country by Spanish missionaries in the 1700s and spread by Native Americans.

"It was a combination that virtually wiped out our native grasses," Poole says. "The grasslands in the San Joaquin Valley looked nothing like they do today."

About a mile of easy walking from the parking lot, we come to an old Yocut settlement. All that remains of their domiciles are small depressions in the dirt.

Atop a nearby granite slab are about two dozen mortar holes of varying widths and depths. The Yocuts used them to pound acorns into meal, a primary food source.

These curious round depressions are filled with water from recent rains.

"We look at them as sterile holes in the ground," Pryor says. "To the Indians who lived here, it was a kitchen."

As Prior answers questions about the former inhabitants, Poole bends down to collect a sliver of obsidian buried in the grass.

The shiny black rock, used for tools and arrowheads, likely was transported from the east side of the Sierra Nevada.

"Through here it's like an obsidian freeway," Poole says.

Red-tailed hawks and turkey vultures soar overhead as we begin climbing toward the tabletops. Wildflowers, one of the first sure signs of spring, are beginning to bloom.

Once atop the flat summit — now you know where Table Mountain got its name — we settle in for a picnic lunch taking in the panorama of green foothills and snow-capped peaks.

The tabletops are actually the ancient bed of the San Joaquin River, Poole explains. About 10 million years ago, a volcanic eruption filled the river with lava, which cooled and solidified over time.

After the geologic uplift that created the Sierra Nevada, softer rocks surrounding the lava eroded away, leaving a ribbon of basalt that can be seen for miles in all directions.

"It's the classic story of how a river bottom became the top of a mountain," Poole says.

One of the most interesting features of the tabletops is the collection of vernal pools formed by spring rains. Before evaporating in the summer, these pools provide temporary homes for rare crustaceans, plants and amphibians.

"Boy, there's a lot of neat stuff around here," says Olsen, cupping in his hand an inch-long Pacific Tree Frog.

The McKenzie Preserve, normally closed to the public, will host an open house March 25 as well as several group hikes through April. Check www.sierrafoothill.org for details.

The reporter can be reached at marekw@fresnobee.com or (559) 441-6218.