The Randall Davey Audubon Center
February 01, 2010
If you are staying in downtown Santa Fe – perhaps with us here at Inn on the Alameda – and you need a quick taste of the natural world, there is no better choice than Santa Fe’s Audubon Center just at the end of Upper Canyon Road, in the spacious entrance to the canyon of the little Santa Fe River. It’s about a two mile drive from the Inn, along some of Old Santa Fe’s most picturesque streets, and while the very last section of the road is unpaved, there’s plenty of parking and a welcoming nature center waiting for you at the end of your short journey.
The Audubon Center’s ground is just beyond the Nature Conservancy’s Santa Fe Canyon Preserve, where there is even more parking available, as well as trailhead access to the network of paths in Santa Fe’s Dale Ball Trail system. The Dale Ball Trails give you a way to to explore the foothills of the Sangre de Cristo Mountains above town – and get some great views – without really leaving town at all. The Audubon Center supports a small network of trails, which are frequently used for their Saturday morning bird walks, and the Nature Conservancy maintains a trail loop in their preserve, with some strategically-placed interpretive signs along the way.
In the early days, a sawmill was built here in the mouth of the canyon – which subsequently became the Randall Davey House – and Santa Fe’s first dam was constructed to hold back a small reservoir. This soon proved insufficient for the growing town, and other small dams were built upstream, higher in the watershed, to impound the spring runoff. Most of the canyon was deforested for firewood. With this movement of attention up-canyon, the area around the Randall Davey House began a slow recovery, which has been greatly assisted by the efforts of the Audubon and the Nature Conservancy. The most remarkable of these rejuvenations is the growing family of beavers that has moved back into the stream.
Although I enjoy spotting birds as much as the next person (not very reliably, I have to confess), the Canyon Preserve also offers other opportunities to explore natural history. There is a short stony trail along the north side of the canyon, just above the beaver ponds, that skirts a window into Santa Fe’s more distant past – a past in which Santa Fe might have looked a little more like Cabo San Lucas than the high desert resort it is today.
The north part of the trail is built on a scree of fractured gneiss that has slid into place along an old metal retaining wall built to keep debris out of the old reservoir below. These rocks are extremely old. They form part of the crystalline basement – the ancient continental crust – that was pushed up here during the birth of the Rocky Mountains some 70 million years ago or so. The gneiss itself is over 1.5 billion years old. Although it was born in an environment so hot, deep, and pressured that the rock could flow like taffy, subsequent movement upward brought it into a cold, low-pressure environment (our environment) where the rock became brittle and easy to fracture.
A little further along the trail, just beyond a section of seriously brecciated (broken) gneiss, layered and blocky grey beds appear, separated by gentle slopes of a powdery soil littered with fragments of rock. The grey layers are beds of limestone, a rock that practically always points to a shallow marine conditions at its time of deposition, and the slopes in between hide easily-eroded beds of shale, formerly mud, which also must have settled out of a body of water. (Shale is not quite as helpful in distinguishing its environment as limestone – it plugs up river channels on land, silts up lakes, softens the contours of the sea floor deep or shallow, regardless) And while sedimentary rocks like these are initially laid down in practically horizontal strata, these layers are strongly tilted in places:
Shattered gneiss juxtaposed against tilted sedimentary strata indicates faulting – a process in which rocks are offset along fractures in the Earth’s crust. These particular layers of limestone and shale aren’t very thick on Santa Fe’s side of the mountain, but if you were to hop over the mountains to the east, you’d find entire ridges worth of the stuff. On this side of the mountain only a few small slivers of the limestones and shales are preserved, and these are inset into the crystalline basement rocks along faults such as the one you’ve just walked across on the trail.
A closer look at the limestone beds gives a much stronger indication of their marine origin:
The rocks are full of fossils – brachiopods (the shells), crinoids (sea lilies), and byrozoans (looking like sea fans) – which strengthen the interpretation that these limestones were laid down in a shallow sea. Such creatures typically thrive in shallow, warm, sunlit waters. The fact that most of the fossils are abraded or broken up into fragments suspended in limy mud (geologists call this a “fossil hash”) also hints at waves and tidal currents dispersing the remains.
These fossils help in another way: they allow geologist to assign the rocks to a specific period in the distant past – in this case, the Pennsylvanian Period (320 -286 million years ago). Reconstructions of the positions of the drifting continents puts New Mexico practically at the Equator at that time. A foreshadowing of the Rocky Mountains – the Ancestral Rockies – were punching up through shallow seas then, responding to stresses set up by the convergence of the North and South American continents. In my mind’s eye, I can picture a calm ocean glittering under a hot equatorial sky, with arid islands of granite shimmering in the distance – like the Sea of Cortez off La Paz – right here, where Santa Fe sits today, 7000 feet above the ocean.
So next time you’re here in town, take a short drive up Alameda Street and Upper Canyon road, get out and stretch your legs, say hello to the nice people at The Nature Store, and have a walk, with eyes either tuned to the past or the present, in this wonderful natural treasure only minutes from the Plaza.