The "mystery holes" at Mount Baldy are probably the remains of trees from when the Dunes moved in around them. We used to encounter them when I was a kid backpacking in the Oregon Dunes.
The sand moves in the tree roots from the inside. Bark lasts much longer and basically helps the hole maintain its shape.
If your reporter called the Oregon Dunes Recreation Area Management, they would or should happily conform this.
- Danial Christensen, Eugene, Ore.