Great for: Geology, nature
Spring Brook North Trail
Park on Hwy. 67 at the Fowler Trailhead. Hike Fowler and take a right on the Spring Book Loop North trail. Just as you begin uphill look 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.