THE RIO CHAMA: A RIVER GUIDE TO THE GEOLOGY AND LANDSCAPES by Paul W. Bauer, Matthew J. Zimmerer, J. Michael Timmons, Brigitte Felix, and Steve Harris, New Mexico Bureau of Geology and Mineral Resources, 134 pages, $18.95
The Río Chama’s headwaters start in the San Juan Mountains of Southern Colorado. The river flows south some 135 miles to its confluence with the Río Grande just north of Española. Its watershed of almost 3,160 square miles is tiny compared to that of many other Western rivers, but it flows through dramatic landscapes that represent hundreds of millions of years of geologic time. These are some of my favorite landscapes in New Mexico, sparsely inhabited country with colorful panoramas in every direction.
The Rio Chama: A River Guide to the Geology and Landscapes is a new guidebook and river guide for boaters, hikers, and other visitors. It contains mile-by-mile maps of the Chama’s 118 navigable miles. The authors have divided their guide into 10 sections with maps showing launch and takeout sites, rapids, dams and irrigation structures, private property warnings, and other information boaters need to navigate the river.
Interspersed with river maps are chapters on local geology, written by experts. Four of the guide’s authors work at the New Mexico Bureau of Geology and Mineral resources at New Mexico Tech, teaching, conducting geologic research, and mapmaking.
Lead author Paul Bauer has mapped and written about the geology of north-central New Mexico since 1982. He and co-authors Matthew Zimmerer and Michael Timmons have led Chama rafting trips for New Mexico Tech’s summer geology field camps. Bauer’s award-winning river guide to the Río Grande, published in 2011, has become a must-have book for boaters on that river.
The Río Chama guide features clear, engrossing, and scientifically accurate descriptions of the rocks and landscapes that the rivers traverse. The geologic information is easy for a layperson to understand and is interspersed with facts about more recent history of the area. The geologic descriptions begin at the river’s headwaters in the San Juan mountains, streams flowing through rocks formed when super-volcanoes exploded 23 to 32 million years ago.
More colorful strata lie downstream, where the Chama River traverses rocks laid down in the Mesozoic Era, the Age of Dinosaurs. The river flows through the youngest Mesozoic rocks first, winding its way through time down to a period when dinosaurs did not yet rule the Earth. The book includes comprehensive chapters of all three geologic periods of the Mesozoic.
The upper part of the Chama River traverses Cretaceous Period rocks, laid down as shallow seas were moving back and forth across the region. Gray shales, sandstones, and coal beds of the Mesaverde Group overlay the dark shales and limestones of the Mancos Group visible at El Vado Lake. Below these strata is the cliff-forming Dakota Sandstone, laid down about 98 to 100 million years ago.
Further downstream, the rocks belong to the Jurassic Period. Pink and green mudstones of the Morrison Formation represent a time when enormous dinosaurs roamed the area, leaving behind their footprints and bones.
The Jurassic Entrada Sandstone, famously painted by Georgia O’Keeffe, makes steep pink, yellow, and white cliffs. These petrified sand dunes were laid down in a desert that covered the Four Corners area some 161 to 165 million years ago. This sandstone forms colored cliffs visible from the river near the Monastery of Christ in the Desert.
The earliest rocks that the river flows through are Triassic Period. The pink and white hills of the Chinle Group are sediments deposited 205 to 228 million years ago. A famous bone quarry at Ghost Ranch dates from this time, when small meat-eating Coelophysis dinosaurs hunted and died along ancient rivers. These ancient siltstones and mudstones were made famous by O’Keeffe’s paintings.
The guide clearly explains how the river flows downward through Mesozoic time, cutting through gray Cretaceous rocks, then multi-colored cliffs of the Jurassic, down to the rainbow-hued Triassic beds.
Below Abiquiú Dam, more recent geological history is visible: the fault that separates the Colorado Plateau from the Río Grande Rift, black lava flows that cap distant mesas, plus a huge extinct volcano forming the highest part of the Jemez mountains.
The guidebook has lovely drawings by co-author Brigitte Felix showing the extinct giants that lived in the Río Chama area, the swamps where they grazed, riverbanks where they hunted, and shallow seas where they swam.
Drone photos by co-author and geologist Zimmerer show how those dinosaur stomping grounds look today.
The authors don’t omit information on later inhabitants of the area. A human timeline includes the Paleo-Indian Period when hunters left traces on Piedra Lumbre Mesa west of Abiquiú Dam. Ancestral Pueblo people built towns, such as Poshuouinge, on high ground above the Chama, farming along riverbanks and on dry mesas. Later came more nomadic peoples: Utes, Comanches, Navajos, and Apaches.
The earliest Spanish settlement in New Mexico was near the confluence of the Chama and Río Grande. The Spanish and Mexican governments parceled out land grants to European settlers. After American occupation, most of those grants were lost to land speculators.
Later came the engineering projects that dammed the river, forming Heron, El Vado, and Abiquiú reservoirs. These dams provide flood control and store water for downstream irrigation and municipal use. Two also generate hydroelectric power.
Today, some 50,000 acres at Chama River Canyon are a wilderness area. A 25-mile stretch below El Vado Dam has been designated a National Wild and Scenic River.
The sections on geology and history are fascinating for someone like me who enjoys learning about the past, but the heart of the book is in its mile-by-mile river log.
Co-author and river guide Steve Harris knows every mile of the Chama well: rapids, hiking trails, camping spots, and places to begin and end boat trips. He is a long-time advocate of rivers, having contributed much of the book’s information on river compacts and water law.
I have canoed on the Río Chama several times, and I wish I had owned the guide back then. It would have kept me from making very stupid mistakes.
When I was in my 20s, I took a visitor from out of town down the Chama just north of Española in my beat-up aluminum canoe. We had to duck under barbed-wire fences that separated local farms. We portaged around many willow- and mosquito-infested acequia diversion dams. One dam we didn’t see in time, went over it stern first, and capsized. After I fished my friend out, she told me she couldn’t swim. The guidebook lists hazards on the lower Chama as “Riverwide diversion dams (10), fences and continuous private land.”
Later, when I was newly married, my husband and I took our new canoe to one of the Chama reservoirs. We paddled athletically north up the lake until a strong afternoon wind and a rain squall came from the south. We turned around but could make no headway to get back to the boat ramp. A kindly motorboat owner gave us a tow, and we arrived at our car just before dark. “Beware of strong upstream winds,” says the river log.
Several years later I took the same canoe when a friend and I went down the river’s Monastery section. She was an expert canoeist, but we hadn’t been warned about Bank Shot Rapid, which almost overturned our boat and slammed us into a ledge. From the guidebook: “Best to keep your distance from the sandstone wall on the right.”
The book, with its maps and helpful warnings, is printed on water-resistant paper. That would be good for boaters like me. However, I think I will go with a guide next time I try the Río Chama. These days, local outfitting companies take clients on river trips, which would suit me fine, since I am now a senior citizen with less appetite than I once had for barbed wire cuts, frantic paddling sessions, and chilly swims.
The guide is available online, as well as in local bookstores and recreation area visitor centers. ◀