North of Walsenburg, Colorado
“Huerfano,” the Spanish word for “orphan,” is an appropriate name for the 300-foot high, conical-shaped butte that stands like a lone sentinel in the arid scrubland some eight miles north of Walsenburg, Colorado. Visible for miles from any direction, it served early explorers as a landmark, signaling the route to life-giving rivers that flowed from the nearby Rocky Mountains.
Huerfano Butte is so striking that the noted land surveyor, General John Fremont, suggested that his stepfather, a wealthy railroad baron, construct his railroad track in the shadow of the premonitory so that passengers could enjoy its uniqueness. It also attracted profiteers who built a fort and then a small settlement nearby. They felt certain that the butte would draw a profitable stream of customers to their businesses.
But I, with some 20 students from Colorado College, saw the butte not just as a curiosity, but as a geologic mystery, a field study organized by one of the professors who required that his class produce a geologic explanation for Huerfano.
After an hour’s drive south from Colorado Springs, we could see Huerfano Butte on the horizon. In contrast to the surrounding gently rolling hills of sagebrush, sparse grass and yucca, Huerfano rose like an…orphaned!…hill, constructed mostly of rocky, black basalt, piled like a massive truck load of boulders dumped onto a flat driveway. It was obviously out of place, an incongruity.
Ironically, although Fremont’s stepfather chose not to build a railroad track past Huerfano Butte, modern engineers did build Interstate 25 no more than a few hundred yards away. From the exit, we followed a narrow dirt road that winds through the yucca along the base of the butte. We stopped, and the professor walked a quarter of a mile north to the landowner’s home to secure permission for us climb Huerfano Butte and explore it geologically. With permission in hand, he returned and gave instructions to his class. With notebooks, rock hammers and bottles of water, they began the trek.
The students began to look like ants as they ascended. After I parked our bus, I decided that I would join in the climb.
The first realization of what I had undertaken came in the form of thirst and hard breathing punctuated by cactus spines piercing my thin pants leg. I quickly learned the importance of water, pacing and body placement.
About a third of the way up, the professor called his students around him like a mother hen gathering her chicks. He asked them about some rock types. Ah, a clue as to Huerfano’s origins. These were not the large, black basaltic-type boulders found higher up, but a fine-grained material that looked somewhat like shale, a sedimentary rock found in ocean beds. Indeed, as I later found out, this was a rock layer called Pierre Shale. But, because of intense heat, it had been altered, or metamorphosed, into a different materialargillite, a metamorphic rock. A deposit of this particular rock extended about 90 yards radially from the butte. We now had the first hint about Huerfano’s origin.
We continued our climb, negotiating the loose rocks and dirt on all fours. Two thirds of the way up, we reached large blocks of basalt slashed with freeze cracks. Although they were unstable in places, the massiveness of the boulders allowed safe passage to the top. As we approached the summit, I could see why Huerfano had been such an important landmark to early settlers. The day was clear and sunny. I could see a thick cloudbank hanging over the “Springs,” some 80 miles to the north. Straight west stood the front range of the Rocky Mountains. They looked closer than their 20-mile distance. South and east went on forever. I felt certain that I could see the Kansas border in the distance to the east. One thing for sure, the Greyhound bus below us looked mighty small.
After hearing an hour lecture on the origins of Huerfano Butte, I, as a layman, can only recall a few reasons for its existence. Apparently, the entire area had, millions of years ago, been underwater. That explains the sedimentary Pierre Slate. A massive uplift then raised the land. As the huge Spanish Peaks, 40 miles to the west, pushed upwards they forced igneous intrusions outward, into the surrounding sedimentary layers. Huerfano Butte became isolated intrusion off by itself, a “volcano that never was,” that is, an igneous intrusion that never erupted through the surface. It never produced the rock ejecta and lava flow that would characterize a true volcano. Subsequently, erosion stripped away the overburden, revealing Huerfano Butte, a volcanic plug. The argillite, a metamorphic rock, exemplifies the intense underground heat that altered, or metamorphosed, the sedimentary slate. As a result of the geologic forces, Huerfano now exists as an orphan, all alone on the arid lands, 40 miles from Spanish Peaks.
The hike back down the butte proved to be slippery and slow. I tiptoed through the cactus patches. Eventually, I made it back to the bus. After the students climbed aboard, we headed back to the interstate for our cruise back north. As we passed the conical butte I still wondered about this isolated volcanic plug, remote, lonely. It really did seem like an orphan in stone.
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