Side Trips from Interstate 5: The Deep San Joaquin Valley

Pleistocene bones abound beneath the Fairmead landfill near Chowchilla. See them at the Fossil Discovery Center of Madera County. Photos by Andrew Alden

Pleistocene bones abound beneath the Fairmead landfill near Chowchilla. See them at the Fossil Discovery Center of Madera County. Photos by Andrew Alden

My previous side trips from I-5 have involved rocks, but that’s not all there is to geology. This suggested route, an alternative to taking I-5 straight south to Los Angeles, will expose you to the southern Great Valley’s hydrology and many excellent, recently excavated fossils.

Start by exiting at Santa Nella — not to patronize the garish set of businesses there, but to take state route 152 east. You’ll go all the way across the valley to Route 99, then south from there to the “Grapevine”.

The first thing you’ll notice, if you haven’t already, is the profusion of canals in the Valley. They come in all sizes, ranging from the Edmund G. Brown Aqueduct (that’s the first one you cross) down to uncountable numbers of field ditches. There are natural streams, but most of the water you’ll see is in canals. This one runs parallel to the San Joaquin River about 6 miles west of Dos Palos Y.

Right next to it, the river that gave its name to the San Joaquin Valley was a sandy ditch in March during the rainy season. In good weather you’ll be able to see mountains wherever you are, either the Coast Range on the west or the Sierra Nevada on the east (as seen here). I believe that there is no place in California where mountains are not visible if the air is clear.

The far end of route 152 meets Route 99. I recommend the old-timey charm of Chowchilla just north of here for a road stop, but otherwise you’ll turn south on 99 and take the very first exit to the Fossil Discovery Center of Madera County.

Photo courtesy Tsing Bardin

The center is across the road from a sanitary landfill, and for a good reason: in 1996, diggers at the new Fairmead landfill uncovered a complete mammoth tusk. Soon it was realized that the site contained a world-class Irvingtonian fossil fauna dating from the mid-Pleistocene about half a million years ago. (There’s a Bay Area connection here: the Irvingtonian is named for the wonderful bone beds unearthed in the East Bay’s Irvington district during freeway construction in the 1940s.)

A paleontological foundation was set up and scientific ties established at nearby Cal State Fresno. Whenever the landfill operators open up a new pit, fossil scientists are on hand to harvest what they can. Bones of mammoths, wolves, sabertooth cats, horses, camels, ground sloths and many smaller creatures are stockpiled and studied at leisure between digs. The Fossil Discovery Center opened its doors in late 2010 and makes an excellent visit whatever your level of interest or expertise. Its outdoor “Pleistocene Water Source” exhibit makes it easy to imagine the lush scene in ancient times.

You can sit out back, next to the fossil washing station, and cast your eye over the surrounding land. I was told that the center has options on some of this acreage, where thousands more fossils surely lie in wait.

Eventually you’ll need to return to 99 and resume your journey. Another stop you should consider is in Bakersfield, where less than 5 miles east of the road on Stockdale Highway is the city’s gracious new Riverwalk Park on the Kern River, which is still a vigorous stream here.

Bakersfield has a lot going on. Another spot to consider visiting is the Buena Vista Museum of Natural History, home of superb fossils from nearby Sharktooth Hill.

Side Trips from Interstate 5: The Deep San Joaquin Valley 21 June,2012Andrew Alden


Andrew Alden

Andrew Alden earned his geology degree at the University of New Hampshire and moved back to the Bay Area to work at the U.S. Geological Survey for six years. He has written on geology for since its founding in 1997. In 2007, he started the Oakland Geology blog, which won recognition as "Best of the East Bay" from the East Bay Express in 2010. In writing about geology in the Bay Area and surroundings, he hopes to share some of the useful and pleasurable insights that geologists give us—not just facts about the deep past, but an attitude that might be called the deep present.

Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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