• Your EMAIL ADDRESS is never used for ANY purpose except to send you updates. EVER!!!!!!

    Join 1,216 other followers
  • MOUNT BAKER: Eruptive history, hazards, research.

    Visit Mount Baker Volcano Research Center websites Main website and the blog These are no longer actively maintained but are still good references [DT, April, 2020]
  • Most recent posts

  • This website first appeared December 6, 2009

    • 801,531 hits
  • Feel free to use the material on these pages.

    Creative Commons License
    This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.
    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

Bellingham area glacial erratics

By Dave Tucker. December 12, 2009

These erratics are close enough to Bellingham that you can walk, ride a bike, or take the bus.

They include:

The Donovan Avenue erratic

The Arroyo Park erratic (scroll down)


The Donovan erratic, in Bellingham, Washington.

This conglomerate erratic is at the east end of Donovan Avenue in Bellingham. It is from the mid-Cretaceous Jackass Mountain Group, eroded by Cordilleran ice from the Cascade Range in southern BC. These rocks can be seen in the Fraser River canyon north of Hope, BC, and along the road opposite the lodge at Manning Provincial Park.  The large rounded pebbles in the conglomerate are primarily volcanic and plutonic rocks eroded from the continent and deposited on a submarine fan close to the coast of North America. The accretion of younger terranes has moved the continental coast increasingly further west than the location when the sediments forming these rocks were deposited.  The boulder was blasted apart in 1965 during construction of I-5. The Skagit River Journal historical website has this photo of the boulder prior to freeway construction. There are other erratics of the same rock in Bellingham. If you visited the rock in place, say at Manning Park, you’d find that the weathered rock can be broken with a hammer. George Mustoe provided a series of photos, Boulder blasting, 1965, of the Donovan erratic being dynamited. Sorry I missed it.

Some locals have long maintained that this rock is a meteorite. That would make it the ultimate erratic! Alas, not true.

Significance of this site: The presence of Jackass conglomerate here indicates that the last glaciation that reached this far south (or further, as we know it did) had an ice component that came out of the interior of BC via the Fraser River, rather than simply being overgrown alpine glaciers from the west flank of the BC Coast Mountains.

Getting there: From I-5, take the Fairhaven Parkway- Alaska Ferry- Chuckanut Drive exit [#250]and head west toward Fairhaven. Turn right at the light on 30th Street and head north three blocks to Donovan. Turn right. At the intersection with 32nd Street, find a place to park and walk 100 feet east to the obvious erratic at the end of the dead end. It is on the edge of a private yard, so act accordingly.

From the rest of the world [i.e., Bellingham], find Donovan Avenue in Fairhaven-Happy Valley neighborhoods and go to the extreme east end, across 32nd Street, where it dead ends at the freeway. WTA bus #105 stops at the corner of 32nd and Donovan.

Jackass Mountain conglomerate outcrop at the bottom of the Microwave Road, right across Highway 3 from the Manning Park Lodge, BC.

The Donovan conglomerate erratic is hard and rounded, difficult to break with a hammer except on an edge left from blasting. Why might there be such a difference in apparent hardness? Probably, because abrasion during transport by the ice removed any relatively soft, weathered exterior rock, leaving the indurated, unfractured interior.

The wonderful ‘Levitating Sphere’ sculpture is made from the Donovan Erratic, and can be found in front of Kulshan Hall at Whatcom Community College. A perfect, polished 39-inch sphere  of conglomerate weighing 3000 pounds is set into a water-filled semi-spherical cup- the base rock, also Jackass Conglomerate, weighs 7000 pounds. The bowl diameter is less than 1 millimeter larger than the sphere. The sphere “levitates” in the bowl, suspended in the thin film of water, and can rotate at the press of your finger. The sculpture was made in 2003 by “Seattle Solstice”. Go to their webpage, click ‘portfolio’ and then visit ‘works in progress’. The upper of the two images on the left shows the work in progress on the obviously out of date website.

Whatcom Community College instructor Doug McKeever rotates the "Levitating Sphere", made from the Donovan Avenue Erratic.

Whatcom Community College geology instructor Doug McKeever spins the 3000 pound "Levitating Sphere".



Your scribe examines the Arroyo erratic, on the Hemlock Trail in Bellingham

This erratic is hidden in the woods in Bellingham’s Arroyo Park. It is quite large- 10 feet high and at least 17 x 23 feet across. It is a slightly foliated hornblende diorite, cut with dikelets of  much whiter, quartz-rich granodiorite. I don’t know the source area, it could be anywhere in the BC Coast Mountains. Or it could have come from the east in the northernmost Cascades in BC, as well- not far from the Jackass Mountain conglomerate that is found in the Donovan Avenue erratic.
Significance: Nothing in particular, other than it is big and easy to reach.

Getting there : A short hike is required to get to this erratic. Arroyo Park is on the south edge of Bellingham, at the foot of the Chuckanut Mountains, along the Interurban Trail. Find your way to Chuckanut Drive (WA Highway 11) in Fairhaven at the south end of town, and head south. From the traffic light at the south end of the Padden Creek bridge, veer slightly left at the school; one mile from the light, turn left at the Y intersection with Old Samish Road. Park on the right after a hundred yards, and take the trail into the ravine of Chuckanut Creek. Follow the trail, staying left, and continue east another hundred yards to the footbridge over the creek. Cross and hike up the hill. Turn left at the first signed trail junction: “Lost Lake 4.1 miles”. This is the Hemlock Trail. Continue up hill on this trail- in less than 200 yards you’ll come onto a prominent bench, and you can’t miss the big old erratic off to your left- a trail goes to it. Please leave your hammer and spray paint at home!

You can also get there by hiking or riding  1 mile down the Interurban Trail from Fairhaven Parkway. The trailhead is halfway between I-5 exit 250 and the commercial center of Fairhaven.

16 Responses

  1. When the new northern section of Bill McDonald Pkwy (in Bellingham) was being constructed, converting it from the old 21st Street several years ago, we saved and relocated a boulder of Jackass Mountain origin that sat between a couple of big trees and in the path of destruction. WWU Geology Professor Dave Engebretson knew about this boulder and requested that our crew move it closer to the Environmental Science building so that his students would have the opportunity to examine Jackass Mountain rock up close and personal. It is now located between the ES building and the Communications building, directly to the South. Is it possible that this boulder was just another isolated erratic or could it be a piece of the Donovan Erratic?

  2. I have had a love affair with the levitating sphere since I first moved to Bellingham in 2006. What a display of craftsmanship! Thanks for posting about the Arroyo erratic. I only knew about the Donovan one – thanks to Doug McKeever, back in the days of Geol 211 ;-).

  3. Don’t feel bad about not knowing about the Arroyo erratic, Glacier Girl Melissa! Dave said I must be getting blind in my old age. I have run near it for years but I was probably too busy not doing a face plant on the trail to notice.

  4. What about the huge rock behind the Mt. Baker Theatre in downtown Bellingham? I suspect it is an erratic

    • Ken,
      The rock behind the Mount Baker Theater in Bellingham is not an erratic, but a remaining bit of Chuckanut Formation sandstone. After construction of adjacent buildings, this is one of the last reminders downtown of the underlying bedrock.

    • Yeah i thought that too, I figured it was an erratic that was left in place as a curiosity.

  5. I seem to recall seeing boulder fragments of material very similar to the Donovan Avenue erratic up near the highest part of Yew Street, east side of the road. Is this the same material, or something else?

    • Yes, Dan, there is another blasted boulder of Jackass conglomerate across the street from the radio station offices. Part of that one was taken to add to the “Levitating Sphere” sculpture at Whatcom Community College.

  6. My wife and I are purchasing a house that is being built in the foothills at the North end of Lookout (or Galbraith) Mountain, about half a mile South of Lakeway Drive. It is a mile or two from the Yew Street boulder mentioned above. We have a good sized conglomerate boulder in the back yard, which we asked the builder to leave intact (they were going to break it up for retaining wall rocks). It is about 6 or 7 feet across and 4 to 5 feet tall. I just started looking into conglomerates and am trying to find out more information about where this may have originated.

  7. I was in the 4th grade at Mountlake Terrace Elementary school. Among other things that year Mr. Shaw got the class involved in rock collecting and chess. We also experienced the Earthquake and an introduction to the Donovan Erratic. A classmate whose father was working on the I-5 project made a presentation of the Donovan Erratic and after they blasted it he also brought in enough samples so everyone in class got a chunk. It was a welcome sample to my rock collection which had grown quite a bit due to the large assortment of geologic samples within the area.

    Sadly our family shipped off to Thailand for a few years and my rock collection along with a lot of other household effects never made it.

    But, I remember vividly that chunk of Donovan Erratic and the excitement over having the sample.

  8. Just found this page by chance and before today had never heard of erratics. Just learnt something new. Thanks 🙂

  9. I was simply searching for info. on the Sumas Mt. hike, and came across your website. I also had never heard of an erratic. I had always wondered how massive rocks end up in certain places. Very interesting! Thank you.

  10. I’m always intrigued by the erratics along South Lake Whatcom Drive, especially those heavy slabs you can see through the trees as you take Cain Lake Road off South Bay.

    • Mark,
      Not sure what erratics you are referring to. If by ‘heavy slabs’ you mean the rocks 100 + feet above Cain Lake road on the hillside, those are bedrock exposures of Chuckanut Sandstone. Dave

  11. This is so interesting about the big rock. My parents moved to 2226 Donovan Ave. in 1945. The house is still there. I would sell the used Pepsi bottles for two cents, get enough money to buy a Twinkie for five cents. Walk up to the big rock and climb up on top and eat my Twinkie. It was so much fun. I was about nine years old then. Often wondered about the story behind the big rock. Thanks to my Niece who did the same thing as I did. She and her friends packed a lunch to eat on top of the Big Rock. Lived on 32nd street.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: