"God's thumb" is a key location in the young adult novel "Holes" by Louis Sachar and in the film adaptation of the book. The top of the mountain in question is named "God's thumb" because it appears as if a rock thumb is pointing to the sky. In the story, protagonist Stanley Yelnats and his friend, Zero, seek refuge at God's thumb.
In "Holes," Stanley Yelnats remembers that his great-grandfather, also named Stanley Yelnats, survived being robbed by climbing to the top of a mountain which he named "God's thumb." Stanley and Zero, running away from the mistreatment they have received at Camp Green Lake, climb toward the God's thumb rock projection on the top of the mountain where they find the onion field that was planted 100 years previously by Sam, an African-American onion salesman whose story is also followed in "Holes." Stanley and Zero hide out in the onion field for about a week, which turns out to save their lives. When they return to Camp Green Lake, they are surrounded by deadly yellow-spotted lizards who refuse to bite the boys because they've been eating nothing but onions.
The rock projection dubbed "God's thumb" does not really exist but was created by the special effects firm Flash Film Works for the movie version of "Holes." The effect of "God's thumb" was layered on top of a mountain near Lake Casitas in Ventura County, Calif.