What it means
Tom’s Thumb is a knob of granite about 140 feet tall standing on the crest of the McDowell Mountains, and from the right angle in north Scottsdale it really does look like a thumb raised over the ridge. Locals use the name for three things that share it: the spire, the steep trail that climbs to its base, and the busy trailhead on 128th Street that is the eastern front door to the Preserve.
Context tells you which. “We did Tom’s Thumb” means the hike, the hardest thing the Preserve asks of an ordinary visitor: about two miles of switchbacks up the mountain’s east face, then a short scramble through boulders to the foot of the spire, with views out to Four Peaks. “We climbed Tom’s Thumb” means ropes and harnesses. “Meet at Tom’s Thumb” means the parking lot, which by mid-morning on a winter weekend is the problem.
The route, the parking strategy and the season are in the Tom’s Thumb Trailhead guide and the north Scottsdale hikes guide. This page is about the name.
Where you’ll meet it
Weekend hiking plans, the best hikes guide, climbing guidebooks, the Marcus Landslide Trail that starts from the same lot, and the city’s summer heat warnings.
Where the word came from
Before it was Tom’s, it was the Dork. That was the name the old-time Phoenix climbers used for the formation, according to both the Mountain Project climbing database and Arizona Highways, back when the McDowells were a long drive into empty desert and the only people who went up there carried ropes.
The new name came out of the Arizona Mountaineering Club, founded by a group of Valley climbers who had learned the craft together. One of its standout members was Tom Kreuser, and the club renamed the spire for him because he was the first member to climb it and report his route. The McDowell Sonoran Conservancy gives the short version: the club “dubbed it after Tom Kreuser.” The year is less settled. Arizona Highways says Kreuser pioneered what is now the standard route in 1965; other club and conservancy accounts give different years for the renaming.
The improvement over “the Dork” was obvious, and the name spread from the climbers to the hikers, and finally to the city, which put it on a trailhead when it opened the lot on 128th Street in 2012.
What it is not
Tom’s Thumb is not Pinnacle Peak, the bigger granite summit a few miles north with its own park and trail, and it is not Thompson Peak, the radio-tower summit farther south along the range. And the Tom’s Thumb Trail does not reach the top of the Thumb. It ends at the base.
The fine print
The spire is a plug of desert granite, and its walls and the boulders around it hold dozens of climbing routes; Mountain Project currently lists 18 on the Thumb itself, and the surrounding area holds many more. The summit is technical climbing only, with routes rated on the climbing scale rather than as scrambles.
The hike is what most people mean, and its numbers are worth knowing. Arizona Highways puts the trail at about 4.25 miles round trip, climbing from about 2,820 feet at the trailhead to about 3,848 feet, and rates it strenuous. Most of the gain comes in the first two miles, on switchbacks that face east and get full sun by mid-morning. The trailhead, opened in 2012, has restrooms and shade ramadas but no drinking water, which is the single most common mistake visitors make.
The record on the name has one hole: the exact date of the renaming. Club sources and magazine accounts agree on the who and the why, and disagree on the when. Until someone produces the club minutes, the mid-1960s is as precise as the evidence allows.