Vanport Limestone Fractures
In the streambed of Hell Run adjacent to the Hells Hollow parking lot, the Vanport Limestone has many deep, wide fractures extending perpendicular across the stream. This type of fracture appears to occur only at this location. During dry periods, such as when this photo was taken, the water in the stream flows into the subsurface upstream from here, where the fractures begin, leaving this stretch of the stream dry. The flow reappears several hundred feet downstream, where the fractures end.