Interesting facts about Tom's thumb. Tom's thumb, located in the Scottsdale, McDowell, Sonoran, Preserve, is a popular hiking and rock climbing destination in the area. This massive granite rock formation stands 200 feet atop a mountain ridge line overlooking Scottsdale, standing out like a thumb. It's named after local rock climber, Tom Cruiser, who was the first to scale it and inspired many others to continually push their climbing abilities. So keep climbing those mountains in your life and maybe someday they'll be named after you. For more useless facts about Arizona, to annoy your friends with, subscribe to our YouTube channel and follow us on Instagram.