There was a large downpour that hit Washington State causing massive slides. The blocks you see here all came crashing down on the hillside.
Once the skies cleared, hikers found plant impressions in the rock and alerted the local paleo community. I was invited to visit just after the slide to photograph the site while George Mustoe took moulds of the palm trunks and trackways.
The slide site at Sumas Mountain revealed many large exposures of fossil plants. Some exposures were 10 feet across. There was great excitement at seeing shorebird tracks and trackways of the large flightless bird Diatryma. Many of these finds can now be seen at the Burke Museum in Washington State. While less abundant, evidence of the animals that called this ancient swamp home are also found here. Rare bird, reptile, and mammal tracks have been immortalized in the soft muds along ancient riverways.