ANCIENT FOOTSTEPS
Massive landslide reveals trove of fossilized plants, footprints

Story and photos by Jeremy Schwartz

Saturated soil squishes underfoot as I trudge through an alien but strangely familiar landscape near Kendall. Though the sky is blue with nary a white blemish of cloud to be seen, water still drips from the tips of the broadleaf plants and palm fronds surrounding me.

Birds flit from tree to tree as I make my way through the underbrush, headed for a slowly running stream about 10 feet ahead. The leaves thin as the stream gets closer.

And then I see it.

Its massive beak and feet are first to break through the shimmering green curtain of leaves lining the stream bank. It plants its two muscular, scaly legs firmly in the fine sand of the stream before it dips its feathery neck to drink.

A gentle breeze ruffles a body full of feathers so black they border on deep purple. Satisfied with its drink, it lifts its head and stands to its full 8 feet in height. We lock eyes and freeze as we become aware of each other’s presence, neither one willing to turn tail and run just yet.
Had I been around roughly 50 million years ago, this is what I could have seen in the Mt. Baker foothills. The creature with the jet black feathers and massive beak is called Diatryma, and the giant, flightless bird was just one of numerous species, now extinct, that once called this area home.

Now all that remains of this ancient ecosystem are footprints in bare rock and the imprints of tropical leaves long since decayed. All would have been invisible had it not been for an immense landslide that has given anyone willing to get a little dirty a chance to look back in time.
The landslide happened in January 2009 just south of Kendall, after the area experienced heavier than average snowfall, said George Mustoe, a research technologist at Western Washington University (WWU). The slide dumped tons of material, including rock, soil and vegetation, into Racehorse Creek and left an 90-foot cliff where the underlying layers of rock are visible.

In the case of this landslide, water saturating the soil underneath the layers of sandstone made the soil particles buoyant, so they were effectively floating in tiny air bubbles, Mustoe explained. This reduced the grip the soil had on the underlying bedrock and, once the soil had absorbed enough water, forced the soil to slip and finally slide. Mustoe said the high-risk conditions for slides are steep slopes, thin soil and steep bedrock, all of which were present in this area at the time of the slide.

“The Racehorse Creek slide area is perfect for that,” Mustoe said.

Mustoe was kind enough to take a day from his summer vacation from WWU and show me the hundreds of fossilized leaves and animal tracks in the underlying sandstone revealed by the slide. The ride there took about an hour from Bellingham, most of which involved driving over gravel logging roads that are often traversed by massive logging trucks.

An hour’s drive from Bellingham took us as far as we could go on gravel logging roads. Then, after another 45 minutes of scrambling over crumbly sandstone and stepping precariously from fallen log to fallen log, we made it to the top of a ridge that faces directly toward the main slide area. Mustoe’s wiry frame easily traversed terrain he had clearly visited many times, while I did my best to keep up.

Fossilized imprints of large palm fronds and smaller tropical broad-leafed plants were visible almost everywhere, but what really piqued my interest were the fossilized animal tracks. Mustoe pointed out numerous small shorebird prints, including an ancient heron or two, but was most excited about the large, thick-toed Diatryma tracks.

Mustoe and a team of volunteers were able to airlift an incredibly well preserved Diatryma print from the area in 2010, but numerous tracks can still be found in the area if you know where to look. Mustoe suggested first trying to find the deep heel print of the giant bird, than looking for three toe prints radiating out from that.

“Almost every time we’ve been here, we’ve found tracks we hadn’t seen before,” Mustoe said.
About halfway through the trip, as Mustoe and I were heading back up one of the talus fields caused by the slide, I asked him if ever thought what placing his hand in any one of these fossil tracks meant. That he was, in 2012, placing his hand where an animal that lived 50 million years ago once stepped. His answer?

“Of course I do. I think about that all the time,” he said. “That’s what interests me about this.”

How to get there:
Drive east on State Route 524 (Mt. Baker Highway) and turn right on Mosquito Lake Road. Look for the bridge over the Nooksack River. Immediately after the bridge, take a left on North Fork Road. Keep following this road as it turns into a gravel forest road, then take a right just before the bridge over Racehorse Creek.

On this road, look for the first major left turn after passing a trailhead on the left. The left will be about five miles after the turn off of Mosquito Lake Road. After this turn, the road winds upward in switchbacks until it comes to an end in an area that has been clear cut. Find the trailhead leading up the slope to the top of the ridge overlooking the main slide area by scrambling over a few ditches in a row that have been dug in the forest service road. The trail entrance is a small cut in the surrounding foliage.

For information on the slide area and how to get there, visit nwgeology.wordpress.com/the-fieldtrips/the-chuckanut-formation/field-trip-to-the-2009-racehorse-creek-rock-slide. X

Jeremy Schwartz is a 25-year-old writer who enjoys most anything prehistoric, especially if it has to do with dinosaurs.