The fences are now in place, and a 1.7-mile section of Carquinez Scenic Drive between Martinez and Port Costa is closed during a two-year, $5.6 million reconstruction project.

Actually, that section of road has been closed officially since the 1980s, because landslide damage made it unsafe to traverse. However, hikers and bicyclists have been using it informally anyway. But now the closure will be more strictly enforced.

Carquinez Scenic Drive was a Contra Costa County road. The East Bay Regional Park District acquired a trail easement from the county last December. Using a variety of federal, state, county and park district funding sources, the road will be converted to a top-notch bicycle and pedestrian trail. It will be closed to autos except for service and emergency vehicles.

Work will include stabilizing embankments, installing drainage systems and rehabilitation of the old road surface. The completed trail will become part of the 500-mile San Francisco Bay Trail, which will eventually encircle the entire bay. So far, 310 miles of the Bay Trail have been developed, much of it in the East Bay Regional Parks. Reopening is expected in the fall of 2014.

Trail benefit hike: The Bay Area Ridge Trail is being built around the bay, and as the name implies, it will encircle the bay via ridge tops rather than shoreline.

An East Bay Hills Ridge Trail Benefit Hike for the trail's East Bay portion is planned from Aug. 28 through Sept. 1. If you go the distance, it's 55 miles from Orinda to Hayward, on trails connecting to and including the Ridge Trail, sharing camp with the East Bay Hills Trails Benefit Equestrian Ride.

This is a fully supported hike, which means the organizers will move your tent, sleeping bag and other gear for you. All meals are provided. Nightly camps are at Tilden, Joaquin Miller and Anthony Chabot parks in the East Bay hills, with entertainment including naturalist talks, stargazing and an equestrian drill team.

Event sponsors are the Bay Area Ridge Trail Council, the Tilden and Wildcat Horsemen, the Metropolitan Horsemen's Association and Volunteers for Outdoor California. This trails benefit has raised more than $160,000 for East Bay Trail maintenance and planning over the last 11 years.

You can join the trek for one, more, or all five days. The cost is $60 per day with a discount for through-hikers. For more details and reservations, visit the Bay Area Ridge Trail website at www.RidgeTrail.org.

WEDNESDAY WALKERS: As long as we're talking hiking the heights, consider joining the park district's Wednesday Walkers at 9:30 a.m. Aug. 28 for a moderate 5-miler between Sibley Volcanic Regional Preserve and Huckleberry Botanic Regional Preserve in the Oakland hills.

Though not long, the hike is steep in places. Meet at the Sibley parking lot, which is on Skyline Boulevard just south of the intersection with Grizzly Peak Boulevard in Oakland. For information, call 510-544-3282 or email cgarcia@ebparks.org.

A LITTLE EASIER: For some less strenuous but informative strolls, join naturalist Anthony Fisher on Aug. 25 at Tilden Nature Area in Berkeley. From 8 to 10 a.m. he will lead a morning walk to see what's going on in the natural world. From 1 to 3 p.m. he'll lead an insect safari. Both walks start at Tilden's Environmental Education Center at the north end of Central Park Drive. The programs are free, and all ages are welcome. For details, call 510-544-2233.

watch those birds: Anthony will also lead a free bird-watching walk from 8 to 11 a.m. Aug. 26 at Martinez Regional Shoreline. The shoreline is a haven for all kinds of our feathered friends. Meet Anthony at the end of North Court Street in Martinez. For information, call 510-544-2233.

stone tools: The ancient skill of stone tool making will be showcased during a "knap-in" from 10 a.m. to 3 p.m. Aug. 24 and 25 at Coyote Hills Regional Park in Fremont.

Naturalist Beverly Ortiz and friends will demonstrate how the ancients transformed chert, obsidian and other stones into spear points, arrowheads and drills. Younger children may watch the process; anyone 13 or older may give it a try. If you want to do so, bring leather gloves and protective eye wear. The event is free. Coyote Hills has an entrance fee of $5 per vehicle. The park is at 8000 Patterson Ranch Road off Paseo Padre Parkway in Fremont. For information, call 510-544-3220.

Email Ned MacKay at nedmackay@comcast.net.