Early the weekend before Thanksgiving, two SUVs loaded with junior geology majors, one professor, camping equipment and burrito fixings hit the road. The small caravan drives about three hours southeast, traversing interstate, state, county and local roads until finally, the asphalt ends.

 They head down Fish Creek Wash, a dry riverbed winding its way through dramatically deep stone canyons.

 Destination? The final exam for Sedimentology. In the Split Mountain area of Anza-Borrego Desert State Park—California’s largest state park and second largest state park in the continental U.S.—students witness the geologic history of the arrival of the Colorado River and the development of the San Andreas Fault as Baja California was ripped away from the North American Plate, opening the Gulf of California, five million years ago.

 “The importance of sedimentary rocks is that they are the Earth’s history,” says Associate Professor of Geology Robert Gaines. “What’s really cool about Pomona College is instead of having to look at some dusty old samples in boxes, we can go camping, and students can actually put their hands on a really complicated succession and try to figure out what was happening during the deposition of these strata, to reconstruct the ancient environments that were present by looking at signatures in the rocks.”

 While the area Gaines and his students explore—which includes wind caves, slot canyons and fossil records like Ice Age mammal footprints—is only accessible to those driving high-clearance vehicles, Anza-Borrego is full of well-marked trails (including part of the Pacific Crest Trail) in its diverse 900 square miles extending from below sea level to 8,000 feet. The park is located mostly in eastern San Diego County, and first-timers can start at the Visitor Center in Borrego Springs for information on the natural history and highlights of the area. Consider visiting in February or March to experience the dramatic blooming of desert wildflowers like the chuparosa, chinchweed and dune evening primrose.

 Call the Park’s wildflower hotline at (760) 767-4684,for updates on the seasonal blooms, or visit www.abdnha.org for more information.

The morning sun has only begun to tint the sky when Heather Williams breaks through thin shrubs to reach the gravelly bank of the Santa Ana River, which is running cool, clear and fast. Williams has come here often over the past two years, mainly as part of her academic research, but also because she finds the site enchanting at the break of day.

She also is drawn by the juxtaposition. Egrets, ducks and other birds wing above as unseen creatures rustle in the dry grass, a bucolic backdrop to the homeless people sleeping in tents deep in the brush, and the distant rush of commuters barreling down unseen roadways. The air carries a tinge of burning garbage as well, from breakfast campfires near the covered-over Tequesquite Landfill that Williams walked past to get here.

 “This is here, this is accessible to us, even when we think that we are surrounded by nothing more than big box stores and concrete and freeways and noise,” says Williams, a professor of politics who teaches, among other courses, Global Politics of Food and Agriculture. “For me it’s a metaphor for our ability to access nature in unexpected places. And it presents us with a choice for the future.”

 For all the natural beauty of this stretch of river, the spot Williams has picked out cuts through suburban neighborhoods three miles southwest of downtown Riverside. The Santa Ana, surprisingly, is the largest river in Southern California, traveling nearly 100 miles from its source on Mount San Gorgonio through the Inland Empire and Santa Ana Canyon—where the 91 Freeway cuts through the mountains to Orange County—and on through to the Pacific at the Newport Beach-Huntington Beach border.

 This geography represents past and future, and the centrality of water to human settlement—people have lived along the waterway for 9,000 years. And  it is the subject of Williams’ book-in progress, River Underground: The Secret Life of the Santa Ana, which looks at the modern evolution of the river from early flood-control efforts through its present condition, amid the region’s expanding population and conflicting demands.

 It’s a convoluted past for this inconsistent ribbon of water. The Santa Ana has raged in massive floods and all but disappeared in droughts. It has had its riverbed paved in sections. And it has been the focus of political battles over who gets to use its water, how it should be managed and the role it plays in regional recreation.

 In fact, there are scores of free access points along the river, from the foothills of the San Bernardino Mountains to Williams’ favorite spot here amid the cottonwoods to where the Santa Ana reaches Orange County’s emblematic beaches. More than 40 miles of developed hiking and biking trails along its length offer oases of nature—and a glimpse of the original landscape—amid the SoCal sprawl.

 Oddly, Williams was drawn to studying the Santa Ana River through a research project she did in Peru on the political overlays to human migration and boundaries, both natural and national. But the local Peruvians wanted to discuss water quality and mechanisms to collect statistical portraits of the health of local rivers.

 That started an evolution of thought that led Williams to wonder about the health and history of her local watershed, and the demands that will shape its future.

 For Williams, this spot along the river represents what has become a consuming area of academic inquiry and a place to generate and share ideas, as she did last summer with a “dream team” of summer research assistants, including Tara Krishna ’14, Clare Anderson ’15 and Minerva Jimenez, Cal State Fullerton ’14. But it also has become a temporary refuge, a place where, on a spring day, “you would see the willows in all their glory. And you would hear the wind coming through the cottonwoods.”

More than a decade ago, when Geology Professor Eric Grosfils first started bringing students to Amboy Crater in the Mojave Desert, he dreaded the last stretch of the long trip, each time hoping the rough dirt road and unpaved parking lot had not been washed out in a storm.

 Fortunately, the path always was intact and the three-hour bus ride always worth it, Grosfils says, because the strikingly symmetrical cinder cone volcano offers such an accessible, boots-on way to teach introductory students about the basics of volcanology.

 Since then, new amenities have been put in place—restrooms, a shade spot and, best of all, paved roads and parking—clearing the way for you, too, to more comfortably visit this desert wonder located right off an old section of Route 66. Reaching the cinder cone simply requires a relatively flat, mile-long hike, and a convenient breach on the west side of the crater wall makes the steep path up to the rim a bit more manageable for those who are in less than impeccable shape. “You can go into the crater and crawl around,” says Grosfils. “It’s fresh. It’s young. The lava flow looks great. The cinder cone is completely intact.”

 Grosfils takes students to the crater during the first few weeks of his introductory geology class, which he teaches with a planetary emphasis. The idea is to give them access to a very obvious volcano that they can roam and get a sense of the scale of things.

 In the class, a lot of numbers are thrown around, Grosfils says, and the visit helps put the figures into context. If the students are huffing and puffing while climbing up the 250-foot-high Amboy Crater, and they know the massive Olympus Mons volcano on Mars is in the ballpark of 14 miles high, “it means something.” “This is a field trip that’s really about observation,” he explains. “It’s about finding out what you can see in the field and building hypotheses from that—things that are testable. … I want the students to be asking questions about what they’re seeing. I want their observations to drive the hypotheses about the processes that go on.”

 While up on the rim, he asks the students to look out at the surrounding desert plain and imagine what they would have seen if they had been standing there watching when Amboy first erupted. He has them estimate the thickness of the basaltic lava flow, and later in the term they consider what shape it would take under the conditions of another planet. On Mars, for example, with all other conditions the same, the lighter gravity would most likely lead to a much taller, though less extensive, volcanic flow.

 For your trip, you can get a little more down to Earth, taking notice of the two nested areas inside the volcano, evidence of two smaller and later eruptions. You also can figure out the direction of the prevailing winds by noticing the absence of sand on one side, a wind streak (also visible to orbiting spacecraft, like similar features on Mars) that forms on the downwind side of the volcano. Amboy Crater’s relative youth—Grosfils says that recent estimates put it at anywhere from 7,000 to around 80,000 years old—makes it a great, unblemished example of a cinder cone volcano.

 But even if you hear explosions and rumbling, rest assured the dormant volcano is probably not the culprit. The boom-boom-boom is likely coming from the Marine Corps bombing range to the southwest, so, along with taking the usual desert heat precautions, make sure you know where you roam.