Geo-stumper: name that monolith!

By Ransom Riggs

Unlike my science-fictional counterparts, I'm not one of those solar-system-wide computer network monoliths, planted by a superintelligent alien civilization and designed to shepherd humanity into its golden age. Nope, I'm just a humble, naturally-occurring slab of rock "“ but at 235 feet tall, I'm among the largest in the world. Anyone care to guess my name?
OK, here are a few hints:
- I'm not the monolith Richard Dreyfuss once famously sculpted from mashed potatoes
- I'm situated 80 miles west of a city whose anagram is "plant rod."
- The smaller rock formations near me are known collectively as "The Needles," because you could fit a whole stack of 'em inside my comparatively gargantuan self.
- Interesting, though admittedly not that helpful: the word "monolith" derives from the ancient Greek words for "lonely" and "stone."
"¦ and extra brownie points to anyone who can name the popular 80s movie in whose climax I am prominently featured.