Palm Frond Fossil

Last Saturday, November 9, son Edward and I hiked around Slide Mountain and the Racehorse Creek landslide, looking for fossils. The hike was more of a muddy scramble than anything else, but we found plenty of fossils and also met up with some of Edward's co-workers and spent most of the afternoon with them doing some more fossil hunting and exploring.

The Racehorse Creek landslide happened on January 5, 2009, after a days of warm stormy weather and rain (what we call here a Pineapple Express). About 500,000 cubit feet of rock and earth slid down the mountain and into Racehorse Creek temporarily blocking the Creek and two days later causing a massive flood of water, rock and timber down Racehorse Creek.

The landslide left a 350 foot cliff in the side of the mountain and uncovered thousands of Eocene fossils, mostly of plants, though bird tracks have also been found. The debris field itself is a jumble of boulders and timber and the best place to look for fossils, though it requires some serious scrambling, but the fossils can be found all over the mountain and we looked in several other places as well.

The area is layers of soft carbonaceous shale which quickly weathers and crumbles and Chuckanut sandstone. The fossils are found in both with inclusions of coal as well. This is a photo of a whole palm frond and pieces of other fronds in shale. The rock is around four feet long and several feet wide, to give an indication of scale, and many of these fossils are massive.