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    Northwest Geology Field Trips, by Dave Tucker, is licensed under a Creative Commons Attribution-Noncommercial- Share Alike 3.0 United States License. You can use what you find here, repost it with attribution to the author, "remix" it for your own purposes, but may not use it with the intent of making money off of it.

    EDUCATORS: Please feel free to use anything you find here that is useful to your mission educating people about Earth science. E-mail me if it would help to have a larger or higher-resolution version of any of the images. tuckerd at geol dot wwu dot edu

Rock Trail, Larrabee State Park

Bud and the thin beds at the overhang.

Thin beds in the Chuckanut Formation along the Rock Trail.

I will post a full geologic guide to the new Rock Trail when the trail is formally opened on April 26th. An email subscription to this blog will deliver the news to you directly. In the meantime, please enjoy other Chuckanut area geology descriptions on my blog.

Fragrance Lake

Raptor Ridge

Oyster Dome

Clayton Beach– a layer of volcanic ash preserved in the Chuckanut Formation

A full listing of localities I describe is here. For a primer on Chuckanut geology, visit this page.

Dave Tucker

Pillows in the Middle Fork Nooksack

Stacked pillows. Stolen from a commercial website. So, sue me.

Stacked pillows. Stolen from a commercial website. So, sue me.

(Click HERE to go straight to the page about the pillows along the road.)

No, pillow lava, silly!

Cross-sectioned basalt lava pillow in the Elbow Lake Formation, Middle Fork Nooksack Road. Click to enlarge.

Cross-sectioned basalt lava pillow in the Elbow Lake Formation, Middle Fork Nooksack Road. Click to enlarge.

I planned a XC ski trip up the Porter Creek Road or elsewhere off the Middle Fork Road today, but it was raining and 41 degrees. Indulging my secret identity as a geologist, I instead poked around in a roadside quarry, looking at pillow lava in the Elbow Lake Formation. A rewarding outing from Bellingham if you have a 2-3 hours on your hands and a deeply felt need to look at some exotic, unusual, and (admittedly) not too beautiful rocks. The saving grace is the lava pillows, and a cup of coffee on the way and on the way back. As an added bonus, there is access to Twin Sisters dunite nearby.

P.S. There ARE some nice roads to ski up and back down off the Middle Fork.

Geology guide to Fragrance Lake Trail (Larrabee State Park)

The Christmas Girls had just finished decorating all the sign posts as I pulled into the parking lot. Very festive! Click to enlarge.

The Christmas Girls had just finished decorating all the sign posts as I pulled into the parking lot. Very festive! Click to enlarge.

I’ve written up a geology guide to the popular Fragrance Lake trail. You’ll find it here. Even if the hike is mostly in glacial till, there are interesting stones in it, and the Chuckanut cliffs are always worth a peak. I do some armwaving about the origin of the big cliffs above the lake, too.

Beach erratic in Des Moines (the one in Washington, not Iowa!)

Last spring I put out a call for intrepid readers to investigate a reported Jackass conglomerate erratic on the beach at Des Moines, between Burien and Federal Way. Thanks to Sandy Bowman and Bud Hardwick for independently investigating. Turns out the large rock is granitic, not conglomerate. Read the article.

Consuelo Larrabee at the Des Moines erratic. Photo by Sandy Bowman.

By the way, does anyone know how I can share Google Earth .kmz files on this website? If you do, contact me via email with instructions:

email address to send reports and photos. I'll credit you.

Guided field trip to Bellingham downtown geology- new date is July 9.

By Dave Tucker   June 1, 2011

Downtown Bellingham's lonely bedrock exposure

This building features igneous, sedimentary and metamorphic rocks, all within touching distance of each other. Click to enlarge.

I will lead a guided field trip to see building stones and the only surviving approachable bedrock outcrop in downtown Bellingham. The walking field trip is open to subscribers of this website, and is oriented toward people without an academic geology background. However, even a geologist may be surprised at the variety of rocks we will see. I will talk about the origins of these building stones, and the geologic stories they record.

Saturday, July 9, 2-4 PM

Cost is $30/person

On this two hour walking trip, we will see a wide variety of rocks: igneous, metamorphic and sedimentary, from many parts of North America and the world. Highlights include: fossiliferous Indiana limestone, the same rock used to face the Empire State Building; exotic stones used in sculptures; seismic hazards in Bellingham; several urbanites and how to tell them from natural stone, and much more. A printed tour guide will be provided.

The trip is limited to the first 20 paid participants. If there is sufficient interest, a second trip can be arranged. I have guided a version of this trip for WWU’s Academy for Lifelong Learning. Based on that experience, this trip will fill quickly, so do not delay.

335 million year old marine crinoid fossils, right downtown!

How to register:

Notify me of your intention to attend via email at

I will provide you with a mailing address for a check. The first 20 paid participants will be accepted onto the trip. A portion of proceeds will be donated to Mount Baker Volcano Research Center.

Chuckanut syncline on State Street is covered up.

State Street syncline then. . .

The little Chuckanut Formation syncline on State Street in Bellingham is now hidden behind a wall. I hope you got a chance to see it. I first noticed this feature over a year ago and wrote about it here. It was certainly the finest example of the axis of a fold that I know of in the Chuckanut, and at a very visible scale. It wasn’t exposed to human view for much over 18 months.This is the second short-lived exposure described on this website to be destroyed or covered by construction- the other was the ‘Samish Hill slab‘, also Chuckanut Formation.

. . . and now. Sigh.

The making of the ‘Levitating Sphere’ sculpture, Whatcom CC

Happy New Year, everyone! I just stumbled across the website for the Seattle Solstice stone sculpture company. These are the folks who made the wonderful “Levitating Sphere” sculpture in front of Kulshan Hall at Whatcom Community College. Go to their webpage , click ‘portfolio’ and then visit ‘works in progress’. The upper of the two images on the left links to a brief slide show about how the sculpture was made. The website is obviously out of date, but no matter. They’ve made other rotating stone spheres, too.

The rotating sphere was made from the Donovan erratic, a Jackass Mountain conglomerate erratic just east of the corner of  32nd Street and Donovan in Bellingham’s Happy Valley neighborhood. The erratic was profiled here on this website.The base was made from another Jackass erratic, on Yew Street Road in front of Woodside Church, across from the KGMI radio station.

Stay tuned for a post in the next day or so asking you can participate in Pleistocene glacial research.

Racehorse Landslide fossils

A fossil tree fern and a modern sword fern from the Racehorse Creek landslide.

Here’s a place to collect 50-million-year old plant fossils from the Chuckanut Formation. The Racehorse Creek landslide, which occurred in January of 2009, has left a lot of small, fossil-bearing rock slabs in the rubble. The field trip description is here on Northwest Geology Field Trips.

Visiting Korean earth science teachers hunt for fossils.

Samish Hill slab- a curtain call.

By Dave Tucker

Saturday, July 31, 2010

Grandson Alec Foote at the site Saturday 7/31/10. Click to enlarge any image.

Construction has nearly completely destroyed the glacially smoothed and striated slab on Samish Hill in Bellingham. The site was featured in a March posting. Now there is an 8-foot-deep pit blasted into coarse facies of the Chuckanut Formation; this will be the home of the new Temple Beth El synagogue. A few interesting sites remain to be seen: coal seams, curiously-textured very coarse-grained sandstone, some coalified fossil branches. If the big yellow tracked crusher is still there, that is worth a look-see. The erratics discussed in the previous story are still there, though getting overgrown by high field grass. TH SITE FEATURED ON THIS FIELD TRIP WILL LIKELY BE GONE WITHIN DAYS, SO DO NOT DELAY. It makes for a quick outing, an hour at most on a sunny day (well, it was sunny when I started this!) this weekend.

How to find the 'Samish Slab'. Click to enlarge

Getting there: These are new directions, as access through the construction entrance is less feasable now. Begin at a foot trail on City of Bellingham right of way at the south end of 47th Street. The trail, ‘paved’ with poorly sorted glacial drift, goes south through shaded and pleasantly cool second [third?] growth forest. Turn left at a T-junction after about 200 yards. The trail ascends slightly, and shortly comes to a nexus of several trails. The construction site is visible off to the left, but instead of crossing over the ‘no trespassing’ sign, continue straight on a trail with low bushes to the left between you and the construction site. You will see one or more faint tracks going left a few feet into the grassy construction clearing. Walk east (right) along the fence at the top of the pit. If there is no work going on, you’ll figure out how to get down into the pit.

The upper part of the drill hole is in competent, fine sandstone. When it entered the poorly cemented coarser sediment, the hole sheared.

Once in the pit, examine the SE corner to see the remnant of a blasting drill hole. At the top, it is smooth and half-round, but lower down, it enters a very friable coarse granule layer and becomes very distorted due to incompetence of the lower rock layer; the drill must have crushed its way through this layer before reentering solid sandstone beneath it. Just to the left are a couple of small coal seams. Walk along the south face of the pit wall and watch for some coalified wood. At the SW corner, a cross section reveals smooth glacial till overlying the ice-planed smooth surface of the slab- an unconformity representing around 50 million years of missing time. This smooth rock surface is about all that is left of the once very extensive striated surface of the Samish Slab.

Till overlies the glacially smoothed erosional surface of Chuckanut Formation sandstone. Alec's hand is on a 50 million-year unconformity

Fay, Alec's 1-foot-long pug, for scale at the coalified wood exposure.

I climbed up onto to the big, yellow, tracked, crusher beside the big pile of crushed rock. This heap is all that is left of the rock that filled the excavation. The climb up was not simple, but the big jaws are very impressive. If you have seen a rock crusher in a geology lab, you’ll be doubly impressed at the comparison.

The tracked crusher with Alec and Fay.

Jaw crusher

The Samish Slab: new expanse of striated Chuckanut in Bellingham

Ah, fortuitous bliss! Here is a field trip to a wonderful, huge slab of Chuckanut bedrock, right in Bellingham, covered with glacial striae, and nicely jointed. And a veritable petrology class of heaped salvaged erratics to boot, including bedded chert and a few pumicious lithic tuffs. But go soon, the place is slated for further excavation and destruction soon!

The 'Samish Hill' slab of Chuckanut. It measures about 200 feet across.