Tom’s Thumb is a granite spire that caps a high ridge on the northeast side of McDowell Sonoran Preserve. This iconic formation is visible from miles around, and has quickly become one of the area's most popular hiking and climbing destinations. A trail extension leads to the Lookout, a bare outcrop with excellent views of the McDowell Sonoran Preserve and McDowell Mountain Regional Park.

Grus - finely eroded granite - acts like ball bearings and can make for a slippery trail, and contribute to the instability of slopes

The first half mile rises gently up a broad, diversely vegetated bajada

Harris's Hawks are social birds that often live in small family groups which hunt together in coordinated fashion

Tom's Thumb is a 140' spire sculpted from once angular and jointed granite

After a steep initial climb, travel moderates on high ridges with a good look down rugged valleys

Mushroom-formations are created underground and eventually take shape through erosion and weathering once exposed to the surface of the earth

Light granite boulders leading to Tom's Thumb contrast sharply with dark and colorful meta-rhyolite and quartzite found higher up on the Lookout

The trail between Tom's Thumb and The Lookout showcases a geological transition zone between the black basalt boulders of the front side of the preserve and the light granite rock gardens of the back side

The Lookout - a worthwhile excursion from Tom's Thumb offers views of the entire McDowell ridge line

This mushroom will eventually topple - it could be water freezing in a crack, heavy winds or a distant earthquake that causes it to tumble

The nearby Marcus Landslide Trail offers a level, flora-driven experience vs the steep, rocky slopes of Tom's Thumb

Brittlebush and creosote line the bajada near the Tom's Thumb Trailhead

The Slip and Slide formation is a popular climbing spot adjacent to Tom's Thumb

Tom's Thumb - made accessible via a new trailhead complex which opened in late October 2012

A Roadrunner near The Lookout - Roadrunners can exceed 15 miles per hour and prey on rattlesnakes

A hiker squeezes between two granite slabs at Tom's Thumb base

Morning sun casts a glow west over the diverse vegetation of the Sonoran Preserve

Up close - straight up from the base of Tom's Thumb - formed by cooling magma beneath the surface of the earth and eventually shaped by erosive forces