Honeycomb Weathering

by T.C. Folsom

An unusual feature of Whatcom County’s geology is the honeycomb weathering seen in outcrops of Chuckanut Sandstone. This creates dramatic and surreal landscapes as seen in my images below. While most of the examples along the seashore are wide shallow cavities with many crenallations (ridges), examples found inland are often very deep holes without much crenallations. If you hike down the Rock Trail from Cleator Road overlook in Larabee State Park, you’ll see holes big enough for adults to climb into.

To see many examples of honeycomb weathering, take the trail to Clayton Beach from the Lost Lake parking lot of Larabee State Park. Time your trip for when the tide is out so that you can walk the shoreline in either direction from the beach. Other examples are seen at Teddy Bear Cove and where the causeway from Taylor Dock ends at the shoreline.

A geologist at Western Washington University studied the development of honeycomb weathering at coastal Chuckanut Sandstone. He proposed that salt water splashing on the rock and evaporating disaggregates mineral grains, while algae on the rock protects the rock under the algae. Therefore the algae-protected rock does not erode as rapidly and results in the ridges that we see.

It is difficult to accept that splashing salt water could create the deep holes seen along the Rock Trail yet not erode broader areas of the sandstone cliff. You can explore alternative origin theories at a website devoted to Tafoni. This term is thought to come from a Corsican and Sicilian words meaning windows.