Organ Pipe Formation

Organ Pipe Formation is a cluster of tall, ribbed rhyolite columns above Bonita Canyon Drive, one of the roadside geology stops on the way to Massai Point. It’s a short pull-off visit, not a hike. Stop if you want a close look at the park’s rock shapes; if you’ve already had your fill of roadside formations, this can be a quick look rather than a longer visit.

The narrow pillars and deep grooves give the formation its organ-pipe look. They’re rhyolite tuff: volcanic ash and debris that compacted after an eruption at Turkey Creek Caldera about 27 million years ago. Cracks and erosion gradually separated the rock into the tall columns you see here.

The formation sits beside Bonita Canyon Scenic Drive as it climbs toward Massai Point. The park says it’s easier to stop at the roadside pull-offs on the descent, so save this one for the way back if you’re driving the full road. The upper drive is limited to standard-width vehicles under 24 feet; trailers and larger vehicles have to stop earlier.

For a photo, keep some of the shrubs and rock at the base in frame. That gives the ribbed columns a sense of height and shows how they rise from the hillside.