Until Wednesday, I had only seen the Valentine Eastern Sierra Reserve from the road, driving up Old Mammoth or coming down from the Lakes Basin. Tucked away in the increasingly developed town of Mammoth, the 156 acre Valentine Reserve offers a time capsule to visiting researchers and members of the public; a place where cabins built in the early 1900s are the only structures in an otherwise pristine wilderness of meadows, streams, and forest.
“The Valentine Reserve is what all of Mammoth used to look like,” said Public Outreach Director Leslie Dawson. “It’s a benchmark by which we can measure the change in our community.”
Established as a hunting and fishing retreat for a handful of prominent Los Angeles families, the “Valentine Camp” passed into the stewardship of the University of California in 1972 as a field research station. Carol Valentine, the last landowner of the original Valentine Camp, ensured this change in order to preserve the unique wilderness area in the midst of a rapidly expanding town.
Today, Valentine Reserve, along with the Sierra Nevada Aquatic Research Lab (SNARL), is one of 38 research stations in the UC system, with 115 elementary school classes, 45 college level classes and 300 research projects associated with the area each year. Dawson, who began a series of summer public outreach programs about 18 years ago, called the Reserve an “outdoor library.” For 16 days each year, that library is open to the public, with a number of walks and talks on subjects including wildflowers, forests, human history, geology, and wildlife.
The outreach programs “get people to see the Reserve and learn a little bit more about it,” said Dawson, who joined the geology walk on Wednesday. Self-described “lay-geology person” Carole Lester led the walk, titled “The Geology of Valentine Reserve,” bringing to life the titanic forces that shaped the Valentine Reserve, and the surrounding area, beginning about 500 million years ago when the first oceans swept through what was once a flat, rolling land and laid down sedimentary rock. No sedimentary rock remains, Lester explained, because the volcanic activity in the area raised the land and the waters receded. At the same time, the volcanic activity “twisted, folded and changed the sedimentary rock into metamorphic rock,” Lester said. She noted that the best example of this could be seen in the colorful layers of mountain rock at Convict Lake. That rock has been dated as many as 385 million years old, she said.
Lester also illuminated the formation the Sierra Nevada mountain range as we know it today, describing the meeting of the North American and Pacific plates about 145 million years ago as “a big Mack truck meeting a VW bug.” The North American plate drove the Pacific plate beneath it, pushing the Pacific plate toward the earth’s core, where it melted and, as it cooled, expanded. “This causes the uplift of the Sierra Nevada,” Lester explained. “This process is still happening.” The rock created during this heating and cooling is called igneous, Lester said, which we see most frequently in this area as granite.
In addition to these slow but monumental changes, the region also boasts one of the most cataclysmic volcanic events in North American history, Lester said. She directed us to look down the Long Valley toward Crowley and illustrated the explosion of the Long Valley Caldera, which occurred some 760,000 years ago when the magma chamber beneath the earth’s crust filled to the point where the crust was stretched too thin, and burst. The event, which “happened in only a few days,” Lester said, deposited ash as far away as Florida.
Standing atop a beautiful moraine, or a hill of deposit left behind by a retreating glacier during the last ice age 12-15,000 years ago, it was difficult to imagine these dramatic and transformative events. Yet the landscape surrounding the Valentine Reserve, which includes Mammoth Rock and the Lakes Basin in addition to the Long Valley Caldera, tells this geological story in vivid detail, if you know how to read the clues. Even in the Valentine Reserve, marks of recent geological history, like the Inyo Craters exploding 600 years ago, still remain. Lester pointed out a majestic, 400-year old Jeffrey Pine that must have been one of the first plants to take root again after the devastation. “Geology is an ongoing thing,” she said.
As we ambled back down the moraine to a beautiful meadow where we concluded the talk, I reflected on the sheer geological diversity of the region, and the many different people, from Native Americans to miners, fishermen to skiers, that diversity has attracted over the relatively short years of human settlement. I had to agree when Lester surmised, “We’ve totally just scratched the surface of this area.”
The 2013 Valentine Eastern Sierra Reserve public outreach programs continue until the end of July. Pre-registration is required, with a fee of $15 for the Outdoor Science Education Program to teach science classes to the children of Inyo and Mono counties. Groups are limited. For more information or subjects of remaining talks, call Leslie Dawson at 760.935.4356 or email her at email@example.com.