^{"Paleo mitigation" work during the dig of the new Caldecott Tunnel bore has yielded fresh insight into a familiar set of rocks thanks to fossils like this Miocene horse molar. All photos courtesy CalTrans and PaleoResource Consultants.}

The fourth bore for the Caldecott Tunnel, which connects Oakland and points west with Orinda and points east, is being dug day and night with the first drive-throughs slated for 2013. Part of the job is what Caltrans contracts call "paleontological mitigation": allowing fossil scientists to salvage resources—"fossils and the deposits they are found in"—that would otherwise be destroyed. A paleo mitigation agreement governs the Caldecott fourth bore project, and scientists shared some of the early results earlier this month.

Fossil hunting is tedious, exacting work, but there are those who love it. Kristin McCallister, a paleontologist for contractor PaleoResource, is shown here during early work at the job site, examining spoils.

The vast majority of fossils are microscopic and consist of plankton or pollen grains. But the big bones are sexy. Let's look at the pictures PaleoResource's Lanny Fisk showed at the CalPaleo 2011 meeting in Rocklin, starting with the leg bone of a rhinoceros.

Here are two vertebrae of a Miocene camel species.

And this is the metatarsal bone of an ancient horse.

Finally here's the upper jaw of an oreodont, an extinct browsing mammal the size of a sheep.

All of these (plus bird, pronghorn and wolverine bones) were salvaged from rocks of the Orinda Formation that are about 11 million years old, a time late in the Miocene Epoch. The researchers also found hundreds of plant fossils for the first time in these rocks, including this laurel leaf.

The Orinda Formation makes up the eastern end of the bore. In the middle is the Claremont Formation, a cherty unit that holds up the highest part of the Berkeley Hills. This 1-inch clam is from the Claremont.

Obviously this shows a change from a land to a sea environment as we go back in time.

At the west end of the bore is the still older Sobrante Formation. Fisk told the CalPaleo audience that this unit has yielded a large fish fossil fauna as well as some leaves and marine invertebrates (clams, crabs and plankton). He was particularly excited about the fish, which somewhat resemble cool-water fish of this age from northwestern Oregon.

One handicap that Fisk mentioned was difficulty getting into the tunnel, where paleontologists can watch the rock face and stop operations long enough to examine and salvage the best fossils. Working the spoils pile isn't good for getting exact locations and geological context for fossils. But the bore will be carried out in two passes, and maybe we can get another look at this unique dig.

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Caltrans punched through the northern end of the tunnel on October 1st, 2010.

Reported for KQEDnews.org by Lisa Pickoff-White.

A Caltrans construction crew on Friday punched through the northern end of Devil’s Slide tunnel that will link Pacifica and Montara. Three years after breaking ground on the project, Caltrans now expects the passage to open in 2012.

Since 1958, Californians have debated what to do about the Devil's Slide, a winding stretch of Highway 1 known for its rockslides, landslides and road closures.

"Highway 1 should never have been built along this stretch," said Ivan Ramirez, a Caltrans civil engineer. "We're always going to have these slides occurring, and eventually we're going to lose Highway 1. These tunnels need to be built."

QUEST on KQED Public Media.

The project consists of twin 30-foot wide tunnels. Upon completion of the project, Devil’s Slide will be the longest road tunnel in California at 4,342 feet northbound and 4,585 feet southbound. At the northern end, a 1,000-foot bridge will connect the tunnel to the valley at Shamrock Ranch.

Construction crews have experienced several setbacks. Crews excavated 10 types of rock that required different lining designs; water poured through the rock when crews were working, so they later had to "drain the mountain." Creating enough ventilation was also a concern.

Over the last three years the crews excavated the rock, removing it to a nearby site. Then they installed initial support elements tailored to the type of rock in different regions of the tunnel. The crews then installed several layers of lining.

Initially, Caltrans had proposed building a bypass through the region in the late 1950s. But public opposition forced the bypass closed. In the 1970s, a Sierra Club lawsuit brought any such plans to a halt as environmental and local groups battled with Caltrans over the bypass through the 1970s and 80s.

In 1995, a large landslide closed the road for 158 days and cost almost $3 million to repair. Later that year the Federal Highway Administration ordered Caltrans to re-evaluate building a tunnel.

San Mateo County voters approved Measure T by 76 percent the next year, changing the county's stated preference from the Martini Creek bypass to the construction of a tunnel. Caltrans broke initial ground on May 6, 2005.

After the tunnel is constructed, the old highway is set to be converted into a trail for hikers and bicyclists.

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As the high-speed rail inches toward reality, it's encountering a thicket of NIMBYism.

We'd been wanting to do an update on the California high speed rail project for months now. (Here's David Gorn's HSR Quest Radio piece from 9/08.) Luckily, there's no bad time to cover high speed rail. The project is so huge, so expensive, so ambitious and so controversial that you could make a whole beat out of it and stay entertained for a good long time.

But if – like me – you're just taking a dip, the first place to check out is the High Speed Rail Authority site. The Authority clearly has deep pockets when it comes to producing animations of the 432-mile train line. Would that the planning process ran as smoothly as those blue and yellow trains.

Click below to use the interactive map.

Your next stop should be this great primer on the technology and issues surrounding HSR, produced by my TV colleagues at QUEST.

I also recommend Robert Cruickshank's California High Speed Rail Blog. Cruickshank makes no secret of his pro-HSR stance — nor of his irritation at those who've put up roadblocks or expressed concerns — but his site is readable and impressively comprehensive. I guess you can count on the train buffs to track every twist and turn of the most ambitious rail project since the Transcontinental Railroad.

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