What's Up with Ellis: Slate Mountain Trail

Saturday, December 13, 2014

Slate Mountain Trail

A hike on Slate Mountain Trail had been on my list of things to do for more than two years when we finally did it on 18 October 2014. We drove north on I-17 to Flagstaff, continued straight on Milton when the freeway ended, passed under the railroad overpass, took the sharp right turn and then turned left onto US Hwy 180 (Humphreys Street). We drove on US 180 for 26.7 miles, passing the turnoff to Snowbowl along the way, turned left onto Forest Road 191 and drove another 1.9 miles before parking at the Slate Mountain Trailhead.

On arrival we hoisted our packs and then posed for a group photograph. On a whim we decided to accentuate height differences by having the two short hikers stand in a gully while everyone else towered over them.

Left to right: Karl Sink, David Beach, Anita Jackson, Daisy Williams, the
author, Betty Wolters and Lila Wright – photograph by Name Withheld

We then paused to read a Forest Service sign that provides a good description of the trail.

Trail description from National Forest Sign

I later read that Slate Mountain, formed between 1.5 and 1.9 million years ago, is a “laccolith, a solid igneous intrusion between sedimentary strata.” The mountain might well have been called Rhyolite Mountain as it is primarily composed of a solid mass of rhyolite that extends for some 5000 feet below the surface. Sedimentary layers were pushed aside by the intrusion and the name Slate Mountain is said to come from one of these sedimentary layers.¹

Slate Mountain is younger than Bill Williams Mountain, Sitgreaves Mountain and Kendrick Peak, but older than Mount Elden and Humphreys Peak with its surrounding summits.²

The trail follows the course of an old road that once led to a lookout tower located atop the mountain.³

The old roadbed makes an excellent trail, rising gently up the slope of the mountain.

We started in a forested area that had been burned over several years ago, the SummitPost trail post quoted above suggested the burn occurred in 2000 and that looks about right from what we saw. As always, the burn area (right) was an opportunity for new growth of different species that thrive in the absence of mature trees.

As an example, I saw several instances of what I think was blue grama grass rings (left). This is a phenomenon that commonly occurs “in resource-limited arid and semi-arid environments” and is thought to occur due to “negative feedback between sediment deposition and vegetation growth” inside clumps of grass. This growth pattern is, however, not limited to blue grama grass and I am no grass expert, so this might well be another species.⁴

Notable also was the abundance of cliffrose in the burn area. It had appeared at first as isolated shrubs (right).

But the cliffrose, with its subtle, offwhite blossoms, became ever more abundant as we climbed higher in the burned area and we were soon traveling through a veritable cliffrose forest.

Slate Mountain Trail with cliffrose shrubs on both sides

We saw several isolated flowers along the way. One that especially struck my fancy was a purple locoweed (left) on which a colorful butterfly had alighted for a refreshing sip of nectar. I made an attempt to identify the butterfly and finally decided that would take more effort than I was prepared to devote to the subject. I did find several that looked very similar, but often the different species seemed to be differentiated by as little as a single spot or a bar connecting two spots. I decided to leave identification to the entomologists.

We had been traveling in a generally northeast direction, but just after leaving the burn area the trail took a sharp turn to the west to climb the mountain slope. We stopped at a viewpoint just near the turn to look out to the south. We had a grand view of Kendrick Peak, slightly west of directly south, and the surrounding prairie spread out below us.

Kendrick Peak, slight left of center, and the surrounding prairie

Just below the top of the mountain we found an Oregon grape plant (right) growing on the road bank. Along with a number of other plants seen along the way, it had been identified and a sign had been posted by the Forest Service sometime in the past. Sadly most of the identifying signs have now gone missing.

At the very top of the mountain the slanting trees (left) bear mute testimony to the strong prevailing winds that sweep the area.

The old road ends just below the top in an area that shows signs of having been quarried. Perhaps someone in the past took advantage of the lookout tower road to haul quarried stone to market. Or perhaps the lookout tower was preceded by the quarry. The trail continues on making a sharp spiral through the leaning trees shown above to arrive in an open area, presumably the site of the old lookout tower. However, we saw no signs that anything had ever been erected there.

We stopped to eat lunch and enjoy the scenery spread out around us in all directions. From our vantage point it was easy to understand why this spot would have been chosen for a lookout tower. The photograph below shows the far-away San Francisco Peaks on the left and Kendrick Peak just right of center.

San Francisco Peaks at left, Kendrick Peak at right of center

After lunch we headed back down the trail, stopping often along the way to admire trees, plants and flowers. On the way up I had noted that the last cliffrose was at an elevation of around 6700 feet and the first Douglas fir tree appeared at about 8000 feet. Having photographed several cliffroses already, I made a special point of photographing a fir (right) on the way back.

Between the fir tree and the highest elevation cliffrose we found a fremont holly grape shrub (left) growing alongside the trail, the only one I saw today.

Not far from the fremont holly grape we found the most colorful flower we had seen all day. It was a skyrocket (right) standing all alone in splendid isolation, barely far enough off the trail to escape being trampled.

Two additional flowers, an Indian paintbrush and a groundsel, were located in the burn area and I don't know how they had escaped my attention on the way up the trail.