November Geology Image of the Month-Dabob Bay Outcrop

Trevor Contreras, Washington Geological Survey mapping geologist, has made a rockin’ discovery, and we are profiling it for November’s Geology Image of the Month!
He explains, “While mapping the Seabeck quadrangle (see context map) in October we found faulted and folded sediments on the east shore of Dabob Bay.  The sediment is thought to be about 100,000 years old, suggesting the faulting is geologically young. The fault planes parallel a magnetic field anomaly that runs through the bay, suggesting this structure is likely fault related. The fault planes we measured generally strike north 30 degrees west and dip to the NE 28 degrees.  We will continue studying the fault and analyze samples to better constrain the age of the faulting with the goal of learning how it fits into the overall tectonics and geological hazards of the Puget Lowland.”

Context Map for observed outcrop in Dabob Bay. Yellow line = Seabeck topographic quadrangle boundary.

Congratulations to Trevor and his team for unearthing (pun intended) a previously undocumented structure that is sure to shed light on the active geology of Western Washington.

DNR geologist, Trevor Contreras, stands in front of the Dabob Bay outcrop.