Estimates by the USGS and Northern Arizona University date Red Mountain at nearly 740,000 years old. The vertical pillars, known as hoodoos, line the central cone of the volcanic cinder cone, "and many dark mineral crystals erode out of its walls," the Forest Service notes.

Once you arrive at the black lava formations, you'll have the option to ascend a ladder into the inner area or scramble up the side of the cone and back down into the formation. Should you be hiking with dogs, the scramble around the ladder is generally a better option. Just be mindful of your footing since it is a bit more exposed.

The trailhead for Red Mountain is located about 25 miles north and west of Flagstaff. Nearly all of the drive is on paved highways, though the last 1/4-mile to the trailhead is on a well-maintained dirt road. There is no water at the parking lot or along the trail, so plan ahead and carry at least 1 liter per person on a warm day, the Forest Service suggests. The hike from the trailhead to the base of the mountain averages about 30 minutes, but it's easy to lose track of time admiring the unique formations and cliff faces once you're standing beneath them.

Sources: https://hikearizona.com/decoder.php?ZTN=101 https://www.fs.usda.gov/recarea/coconino/recarea/?recid=55160