LAUSR

For several years during and after college, I worked as a guide on the San Juan River in southeastern Utah. The San Juan is not a river one seeks out for its rapids and the thrill of running whitewater. Instead, what attract many visitors to float its muddy waters even in midsummer, when the flow drops to a trickle, are the surroundings: sandstone cliffs that host cliff dwellings and rock art panels, canyons with meanders incised more than a thousand feet into Permian and Pennsylvanian limestones. One of the oldest units exposed in the canyon is of particular interest to a subset of river runners. An intermittent layer of algal mounds with “moldic and vuggy porosity” (a phrase that always stuck in my head for sounding vaguely disgusting but means, basically, holes that form from dissolving shells and rock) exposed near Eight-Foot Rapids is the same unit from which major oil companies have extracted hundreds of millions of barrels of oil. Along the river, you can put your hands on it, trace the shape of the mounds, and sniff the oil seeps in a few places (Figure 1), but 20 miles east, in the Aneth oil field on the Navajo Nation, it lies 6000 feet beneath the surface. Each summer, the company I worked for took several boatloads of reservoir engineers and the occasional petroleum geologist down the river to see the rocks they had only encountered in a model, sitting in front of a computer in Houston. None of the engineers were geologists by training; most were uneasy in the outdoors in general, and many found the intensity of the sun and the landscape overwhelming. When we parked the boats at the beach at Eight-Foot and led them on the short hike up to the outcrop that was mercifully in the shade, they were giddy with the heat and the novelty of the situation. Over the course of a short lecture from the attending geologist, they would slowly come to their senses, eventually realizing that we were sitting in the reservoir. They would reach out timidly to touch the rock and say things like, “That’s a vug?” and “This is what limestone actually looks like?” As a college student majoring in geology, I laughed and felt smug in my superior knowledge and understanding of the real Earth, the real reservoir, whereas they knew only simulacra. I liked to think they went back to their computers enlightened and humbled, recognizing the field as the touchstone for their work. In reality, I suspect they returned sunburnt and dehydrated, and perhaps prone to forget about the shockingly irregular porosity of the real rock. And in reality, of course, I had more than a few comeuppances—in the field and otherwise—about my supposedly superior knowledge. The word “touchstone” came to my mind as a metaphor for “the field” as I considered the four articles in this issue that address field experiences. All emphasize the foundational nature and critical importance of learning in the field, which drew me to the word, but I thought I might be missing something in thinking of a touchstone as, more or less, “the foundation one should always be in touch with.” So I looked it up, using my favorite source for deep definitions, the online Oxford English Dictionary. What pleasure to be had! I was indeed missing something. Perhaps not surprisingly, the earliest use of the word touchstone was an actual stone, a black marble used as a building stone. Nearly as early, however, was a second use—also a real stone but something more like a streak plate: a fine-grained dark rock on which purported samples of gold or silver would be rubbed, and the resulting mark compared to samples of known purity. It is the latter use that led to the figurative definition of touchstone that is used most frequently today: a criterion against which the value or genuineness of something is judged. The field—the reality of Earth in all its complexity—is a geoscientist’s touchstone, the criterion against which every geologic map, every climate model, every visualization of change over time, every reconstruction of the past is judged. For many geoscience educators, students’ ability to experience the field is the criterion against which many courses and programs are judged. In their landmark synthesis article, Mogk and