Park on Hwy. 67 at the Fowler Trailhead. Hike Fowler and take a left on the Spring Book Loop North trail. Just as you begin uphill. keep an eye out for wavy-looking rock surfaces on your right (west) side. These are actually exposed cliffs of Dakota Sandstone, and 100 million years ago, this area was a sandy beach, now preserved in the rock.
Resources: Here’s an excellent educational, self-guided trek put together by the City of Boulder.