List of erratics (updated August 2022)

We maintain a list of erratics found during our 2020 Great Erratic Challenge and have added some updates (2022) at the large end.  We added Pokorny’s Rock and Peregrine Rock to the original list of the biggest; below are pictures of each. We’ll update these as new giants are found and documented. Click here for the latest compilation (Aug. 2022).

This is a gigantic erratic on the ridge above Tamanowas Rock in Anderson Lake State Park. Eric Nagle (finder) for scale (6 ft).  Longest dimension is 50 ft. Roughly 20 ft high, partially buried. The rock appears to be a metabasalt or gabbro from the north.  The rock is alongside the trail that goes from Tamanowas Rock to the northeast side of Anderson Lake. Easy access from the parking lot at Tamanowas Rock. About a 1.5 mile roundtrip, takes 2 hours plus you can see Tamanowas Rock, which is an adakite.

The second largest erratic (currently) is Pokorny’s Rock on the appropriately named Valley Rock Farm.  This erratic is owned by Mark and Tami Pokorny of Tarboo Valley. The rock appears to be a metabasalt and is hard to approach since its surrounded by a thicket of Himalayan blackberry canes.  This is on private property, but can be seen in the valley bottom to the west from Dabob Road.


If you find an erratic more than 10 ft (3 m) long, please let us know and we’ll add it and the data to our list. Rock on!.