Sedimentary geology at Teddy Bear Cove, Whatcom County

Adena Mooers points to the sharp facies change from sandstone to conglomerate at Teddy Bear Cove. Click to enlarge any image.

Teddy Bear Cove has shoreline exposures of west-dipping Chuckanut Formation conglomerate, and  a couple of nice swimming beaches. It is a Whatcom County Park on Chuckanut Bay reached by a short trail from Chuckanut Drive.

Chuckanut geology near Teddy Bear Cove.

Getting there:    The trail head for this and several other fine hikes in the Chuckanut Mountains is at the North Chuckanut trailhead on Chuckanut Drive (Washington 11)  just south of the junction with Old Samish Road. Walk up the trail to the Interurban Trail, then proceed south, crossing California and Spokane Streets. In 6/10s of a mile, the trail down to Teddy Bear branches to the right and crosses busy Chuckanut Drive. The trail then switchbacks down through the woods to cross the railroad tracks in 1/4 mile.

The geology:       I recommend crossing the tracks obliquely to the left to find the white crushed shell beach on the south side of the bedrock point separating the beaches. Conglomerate on the south edge of the rocky point has a nice sharp contact with a bed of coarse sandstone immediately underneath and provides a fine illustration of the concept of ‘strike’ and ‘dip’ and the ‘right hand rule’. (Click for primer about structure on this website.) The contact between these two facies of the Chuckanut Formation strikes 155° and dips 55°. (scroll down)

The compass lies along the line of strike of these beds. They strike 155 degrees using right hand rule.

The edge of the Brunton inclinometer is aligned with the dip of the beds. The level indicates 55 degrees of dip.

The dark clasts are rounded phyllite. Kim's fish for scale.

The conglomerate consists of pebbles of several different rock types in a matrix of sandstone. The pebbles are matrix-supported. ‘Matrix-supported’ means that the pebbles are dispersed within the finer sandstone, rather than touching each other. If that were the case, then the conglomerate would be ‘clast supported’. The pebbles aren’t all that rounded, but they are round enough to be conglomerate rather than angular ‘breccia’. The most prominent pebbles are dark, with skinny white quartz veins. These are clasts derived from the Darrington phyllite, which is probably the metamorphic rock beneath the Chuckanut around here. However, the contact is not exposed anywhere north of the Lake Samish area, and is probably a ways below the surface here. Presumably, the phyllite predominates because in the Eocene the river that deposited this sediment was eroding an outcrop of phyllite, and dropped the pebbles here. Other rocks I noticed among the pebble clasts  include white ‘bull’ quartz (probably derived from quartz veins somewhere), and some reddish chert. Darrington phyllite is full of quartz veins, but I’d be surprised if the fairly well-rounded pebbles of quartz came from that rock: quartz is a hard mineral, and has to be subjected to a fair amount of stream transport to become rounded. Folding then tipped the Chuckanut beds; these at Teddy Bear are on the common limbs of an anticline/syncline pair running northwest-southeast (see the image at the top of the page).  The anticline itself is plunging down to the northwest. The anticline’s axis is near the trailhead. You passed a few outcrops of  the sandstone facies of the Chuckanut Formation along the Interurban Trail. This website’s has a Chuckanut Formation page , with links to other field trips.

broken shells and beach glass at Teddy Bear Cove.

The beach consists of crushed shells. I recognized bits of barnacles and clam shells. There is some sand interspersed, perhaps eroded from the Chuckanut. You can wade out quite a way, and enjoy a nice swim here.

Teddy Bear was a renowned nude beach “Teddy Bare Cove” in those days). The freight train often slow down in nice weather so the engineers could enjoy the scenery; sometimes they would toss cold beers out of the windows. Whatcom County bought the property in the late ’80s or early ’90s, and that ended the tacit tolerance of nudity. The alternative was to let the property owner develop the hillside and eliminate decades of public access to the two little beaches. You might still find a holdout sunbathing or swimming in the all-together, but the good ol’ days of cheek-by-jowl nekkidness have passed. But, you didn’t come to this webpage to read about THAT, did you?

Bob Mooers at the till/Chuckanut contact. HIs left foot is on the till, his right is on Chuckanut.

If the tide is out far enough, you can walk a barnacle-studded ledge north beyond the conglomerate-sandstone contact, right along the seaward face of the short cliff. Back at the RR tracks, find a trail going up to the top of the point. The madrona trees up here are all dying, alas. Pebble-studded glacial till lies on top of the Chuckanut at the cliff’s edge right above the southern beach. It is entertaining (well, to some people) to compare the appearance of this till with the pebbly conglomerate.

The northern beach at Teddy Bear. Hey, the place needs some swimmers!

At the north end of the point, a trail drops down to the north-facing wind-protected curve of sandy beach- true sand rather than shells here. Red bricks are found in the water. According to historian Wes Gannaway, these are remnants of a brick-making operation that was here during the early 1900s. Clay was mined from a shale bed up the hill toward Chuckanut Drive, and th point was originally known as ‘Brickyard Point’. Chuckanut Bay was a big sandstone shipping site in those times;  a large quarry 1/4 further south along the tracks exported plenty of sandstone blocks for rebuilding San Francisco after the 1906 earthquake and fire.

On the way back, note all the vesicular lava in the ballast around the train tracks.

9 Responses

  1. […] here to go to the full page. LD_AddCustomAttr("AdOpt", "1"); LD_AddCustomAttr("Origin", "other"); […]

  2. The Day Brick and Clay company had a brick factory on the point during the first 2 decades of the 1900s. The main office was in Fairhaven. The point’s first name was Brickyard Point. The clay for the brick came from an outcrop of clay rich shale in the bluff about half way up. If you go from the north side of the point back into the woods across the tracks you can find lots of “culls” (bad bricks). Lots of local BBQ pits have been made from these cast off bricks. A cull is a brick that is over-fired, broken during processing, or two or more bricks stuck together.

  3. Dave, I can’t shed any light on the brick fragments you write about, but it is interesting that large sailing ships used to come right into Chuckanut Bay….an impossibility now, ever since the railroad causeway was built. Rapid sedimentation coupled with restricted circulation has largely filled in the bay. Also of interest to readers is that if one drives or bikes to the end of Fairhaven Ave. and walks along the north shore of the bay at low tide, as they near the tracks and tunnel they will see the sedimentary beds dip east, then level off, then dip west…all within the span of a few tens of meters. It isn’t every day that one can visually observe the axis of a large anticline like this, not in this heavily-vegetated area!

    • Doug,
      I didn’t know about the exposures near the tunnel in Chuckanut Bay. IU’ll hve to go check them out unless you go first and direct people to them via this website (subtle hint). I also think that the ships that hauled sandstone from the quarry anchored, or moored, south of Teddy Bear right off the quarry, rather than entering the restricted waters that are now inside the RR trestle. Chuckanut Creek must have been dumping sediment into that bay even before the trestle, though admittedly the head of the bay must have been deeper back then.
      DT

  4. Dave: I am 90% sure that I have seen pictures in the local museum of tall ships WITHIN the now-shallow eastern portion of Chuckanut Bay, and once talked with an elderly gentleman who lived on the bay who also maintained that in his youth (that would have been about 1900 plus or minus a decade or two, based on his age then and the fact that this conversation was at least 20years ago) he personally saw ships within the bay. He also told me that he believed that after the causeway was constructed for the train tracks, logging and more recently home construction around the slopes draining into the bay caused rapid runoff, erosion, and sedimentation. Alas, I didn’t get his name so this is merely anecdotal information and not authoritative.

    While not as cool as the “best little syncline in Bellingham” you wrote about that is now obscured by new construction, the anticline I wrote about will be visible for a while.

    To get to the place where you can cross and see the anticlinal axis, while heading south on Chuckanut Drive (Washington 11) just north of the junction with Old Samish Road, turn right onto Fairhaven Street and follow it to its end. There is limited parking there. You must go at a fairly low tide in order to walk along the north shore to the place of interest, the lower the better (but don’t get trapped, so go on an outgoing tide. Tide predictions for Chuckanut Bay are here:

    http://www.co-ops.nos.noaa.gov/noaatidepredictions/
    NOAATidesFacade.jsp?Stationid=TWC1169

    Or go to my webpage and to Links then to Tide Tables. This one is from NOAA and you scroll down to find predictions for Chuckanut Bay.

    Walk along counterclockwise along the right side of the bay (water is on your left) for approximately 0.5 mile. When you get closer to the traintrack ahead, watch the bedrock outcrops on your right. At first the beds are inclined (dip) back toward the direction you have come from, then in a few tens of meters they level off. Walk a few meters farther and note the the layers are now dipping in the direction you are going. You have crossed the axis, and didn’t even have to pay any more taxes! (dumb, I know, but cheap rhyme)

    About 50 yards before you reach the tracks, there is a prominent bedrock ridge about 30 yards long. This is formed by some resistant sandstone and is along the strike of the southwestern limb of the anticline. There is another smaller ridge very near the tracks, also parallel to the strike of the same anticlinal limb.

    Another way to get there that is much shorter crosses private property so I am not going to divulge it here. NO, I haven’t gone that way myself.

  5. I know that sometime in the early 1890s there was talk of making the north end of the bay a drydock prior to the railroad crossing. GN made the crossing and arrived in Bellingham Bay in 1903. I believe the Navy looked at the location but couldn’t figure out how to deal with the silt buildup. Wes

  6. I am a student at San Jose State University, CA – recently moved to Washington and finishing my degree. For my upper-division geology class, we had to explore a geologic location and construct a report/field guide.

    Long story short, I couldn’t have done it without the fabulous and in-depth information on your website! The field trips helped me decide where to go and point out what I should look for, as well as providing additional books and references. I ended up choosing Teddy Bear Cove/Chuckanut Drive and Mountain as my subject so I could take my husband, daughter, and our two dogs along for an educational and very fun afternoon!

    I’ve enjoyed learning so much about the local geology here in Bellingham. I can’t wait to head out on another of your field trips!

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