New geo field trip to Chuckanut rocks posted on this website

Dear Friends,

P1040812 rsz mark

Outcrops along the road.

I just posted a new virtual field trip. It is a 3-mile round trip walk on a logging road in the Chuckanut Mountains just south of Bellingham. It examines near-continuous exposures of a variety of rocks in the Chuckanut Formation. The road is gated so no vehicle traffic.

You will see conglomerate transitioning to sandstone and vice versa. The trip describes the dip, or tilt, of the rock layers, and finishes up at a quarry in remarkable conglomerate. Plus a very nice view down the length of Lake Samish. P1040814 rsz mark

14 Responses

  1. Sounds interesting, but regional setting, age, etc. would make it more meaningful.

    • Ed, thanks for the comment. In the , I said a couple times that the Chuckanut is Eocene, around 50-million years old. Also follow the link to read more on the Chuckanut.

    • Hello Ed. Thanks for the questions. I believe I stated in several places that the Chuckanut is Eocene, around 50 million years old. For more on the Chuckanut search for some of the posts I have on our backyard Formation. Dave

  2. I was amazed to see the amount of conglomerate strung along this road all the way to the quarry when I visited this site a few years ago, and wondered if it had any connection to the conglomerate at the waterfall in Silver Creek across I-5 to the north.

    • Hey Keith, it is very possible they do. The limb of the fold curves around, crosses the freeway, and runs up along Silver Creek. If you go to the stat4e LIDAR map, linked in teh story, you can zoom in and see the quarry. You can almost follow the approx bedding plane around ti Silver Creek and it is close to the the conglomerate wall in Silver Creek. Some very detailed mapping might correlate them, but with the jungle and all….

  3. I’m happy to see this! I’ve been hiking up there for years (usually coming up from the lake samish side) and have always wondered about the geology up there. Thank you

    By the way, any sources on the geology of the lake samish basin & how it was formed?

    John Jenkins

  4. Dave, many thanks to you and friends for this virtual field trip! I learned so much! I love how you point out both what you know and what the mysteries are. – Anita Kay, Olympia WA

    On Fri, Jun 26, 2020 at 12:14 PM Northwest Geology Field Trips wrote:

    > magmatist posted: “Dear Friends, I just posted a new virtual field trip. > It is a 3-mile round trip walk on a logging road in the Chuckanut Mountains > just south of Bellingham. It examines near-continuous exposures of a > variety of rocks in the Chuckanut Formation. The road” >

  5. I’m sorry I missed it we were in the Methow Valley.

    • Patrica, I didn’t lead an advertised trip, I just walked the road and described what YOU can see if you do the same. Dave

  6. Dave,

    Good to see you “back in action”. Using your book for reference in a number of my senior college classes. Also strongly recommending.

    Gene Kiver

  7. Dave, I know erratic are old news, but just in case you have a collection to drop this into, I came across a bit of rock I’d be pleased to have sit next to my driveway!

    On Thompson Road, just west of Hiway 9. Looked maybe 9, 10 feet tall, by 15 feet front to back.

    On Fri, Jun 26, 2020, 12:15 PM Northwest Geology Field Trips wrote:

    > magmatist posted: “Dear Friends, I just posted a new virtual field trip. > It is a 3-mile round trip walk on a logging road in the Chuckanut Mountains > just south of Bellingham. It examines near-continuous exposures of a > variety of rocks in the Chuckanut Formation. The road” >

  8. I walked this yesterday. Flowers everywhere. Great view of Lake Samish and the Chuckanuts from a new perspective. Your notes on the geology let me see the landscape and road cuts in a way I never did before. Thanks! Keep the tours coming!

  9. FWIW, just looked up that erratic on google maps and find it listed as 239 Thompson Rd, Sedro Wooley.

    On Fri, Jun 26, 2020, 12:15 PM Northwest Geology Field Trips wrote:

    > magmatist posted: “Dear Friends, I just posted a new virtual field trip. > It is a 3-mile round trip walk on a logging road in the Chuckanut Mountains > just south of Bellingham. It examines near-continuous exposures of a > variety of rocks in the Chuckanut Formation. The road” >

    • Hello Mike. 239 Thompson road is near Cain Lake, not near Highway 9. 239 Thompson Lane is in Sedro a bit EAST of Hiway 9/20. No erratic shows up in the satellite view.

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