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    Visit Mount Baker Volcano Research Center websites Main website and the blog These are no longer actively maintained but are still good references [DT, April, 2020]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

Dickerman Mountain geology guide posted

Hi friends! Remember me?

P1030402 mark

Stacked lava flows below the summit of  Dickerman Mountain. Click to enlarge.

A new geology field guide has been posted on this website. This one gives you something to do while you huff and puff your way up through the 45-million-year-old Barlow Pass Volcanics on the Dickerman Mountain Trail. The mountain rises above the South Fork Stillaguamish Valley, and is reached by the Mountain Loop Highway east of Verlot and Granite Falls. The trail is a steep mother, gaining 4000′ in just over 4 miles. The summit gives spectacular views into the Monte Cristo area peaks and Glacier Peak. I hiked the trail on July 3, 2016 with my friends Charlie and Scott Linneman. The views weren’t great due to clouds, but I got to examine some North Cascades rocks I wasn’t familiar with. The story is online, here.

New Geology hiking guide published on this website: Ridley Creek Trail, Mount Baker

Link to Ridley Creek Trail geology guide:


Foot bridge over the Middle Fork

Foot bridge over the Middle Fork

Ridley Creek Trail begins at the end of the Middle Fork Nooksack Road on the southwest flank of Mount Baker. The trail accesses the heather meadows of Mazama Park and on to Park Butte Lookout. Along the way see forested latest Pleistocene moraines, glacial till from Canada complete with quartzite pebbles from the Rocky Mountains, limestone, lahar and ash deposits, a close up of the Cathedral Crag lava that predates Mount Baker, and finally, great views of Baker, the Black Buttes, and that enigmatic slice of the mantle, the Twin Sisters Range. Read the geology guide here.  Enjoy!

Dave Tucker

Guided geology field trip to Schreibers Meadow cinder cone

The NCI field trip to Schreibers Meadow cinder cone is booked up.


Dave Tucker

Mount Baker Volcano Research Center subscription website

The bushwack up to the cinder cone rim. Click to enlarge. The bushwack up to the cinder cone rim. Click to enlarge.

North Cascades Institute is offering a guided geology field trip to the 9500-year-old Schreibers Meadow cinder cone on the south flank of Mount Baker. The trip will be led by MBVRC’s Dave Tucker. The date is July 6th, and costs $95. Register at the NCI website:


The Schreibers cone is the only one in the Mount Baker volcanic field. It is located in old growth forest at 3500 feet elevation in Schreibers Meadow, just 1/2 mile from the end of the road. The trip will walk a short distance along the Park Butte/Railroad Grade trail, then veer off cross country (huckleberry meadow and some ponds) before the final 130′ climb up a steep forested slope to the crater rim. We’ll walk down to the soggy shores of the two crater lakes, and up to the opposite rim. After…

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Fidalgo ophiolite field trip, Part II- Mount Erie

Gabbro at Stop 1. Note the pale vertical dikes near the yellow hammer. Click any image to enlarge.

Gabbro at Stop 1. Note the pale vertical dikes near the yellow hammer. Click any image to enlarge.

A self-guided geology field trip to the second part of the Fidalgo ophiolite (oceanic crust section) is posted here. This field trip visits intrusive and sedimentary rocks on Fidalgo Island, including Mount Erie. This is the second installment in the ophiolite series, which started at the chunk of the mantle at Washington Park.

The April 12th guided geology field trip sponsored by Mount Baker Volcano Research Center will visit some of these rocks. Registration information is on the MBVRC website. If you have been waffling, time to be decisive- the trip is nearly full!

The view south from Stop 2 at Mount Erie.

The view south from Stop 2 at Mount Erie. Here we see an island in Lake Campbell, on Fidalgo Island. Skagit Bay stretches off to the south.

Geologic tour along the Dallas Road Waterfront Trail, Victoria B.C.

Dark dike of magma invaded a larger body of pale felsic magma. The dike was broken apart. This is at Holland Point. Photo by Glenn Jareshko.

Fascinating geologic relationships can be seen  at Holland Point.

The third geology field trip along the city of Victoria’s shore has been added to the website. This one walks the city’s south shore along the Dallas Road waterfront trail from Clover to Holland Points. The trip description is largely the work of Gerri McEwen, who just completed her undergraduate honors thesis on these rocks at University of Victoria.

The thrust fault has placed older rocks on top of younger rocks.

Southern Vancouver Island thrusting has placed older rocks in the hanging wall over younger rocks in the footwall. These terms are explained in the Dallas Road field trip.

The relationships between these coast rocks are complex. There has been repeated intrusion, faulting,and metamorphism during accretion of an island arc and offshore terranes against Wrangelia after the latter giant terrane had collided with North America. Do you know the meaning of the terms ‘hanging wall’ and ‘foot wall’? Go to the Dallas Road field trip webpage to better understand the origin of these terms.

Some of the rocks are beautiful and well worth the visit. Take your camera!

A bit of the mantle: Washington Park, Fidalgo Island, Washington

The 'snake-skin' texture of serpentinite lends its name to 'ophiolite'. This is a nice example near the foot of the stairs.

The ‘snake-skin’ texture of serpentinite lends its name to ‘ophiolite’. This is a nice example near the foot of the stairs.

A geology guide to ultramafic rock at Washington Park, near Anacortes, is now available on Northwest Geology Field Trips. Click here to go straight to the field trip! The rock is the metamorphic rock serpentinite, and was originally in the earth’s mantle below oceanic crust. Exposures are found along the dramatic rocky shore and on bare rocky knobs above the coastal cliffs. A single essential outcrop is highlighted in this quick self-guided field trip. The description explains what ‘ophiolite’ is and points out spectacular glacial polish at the same outcrop.

Coming soon:

  • Mount Erie- Fidalgo ophiolite Part 2
  • Finlayson Point, Victoria
  • Rock Trail, Larrabee State Park
  • ?????

Do you have field trips to share? Please do. Let’s branch out to places in southern and eastern Washington. I’m happy to help you write your guide . Contact me via comment or email:

send email here

send email here

Giant Cairn in the Wharf Roundabout, Bellingham Washington

Some guy in a funny hat looks at the giant rock cairn in the roundabout. Hey! Wait I think I know that guy! Where're the cats?

Some guy in a funny hat looks at the giant rock cairn in the roundabout. Hey! Wait I think I know that guy! Where are the cats?

A number of Bellingham people have written me for a geological description of the 12′ rock cairn in the middle of the new roundabout at Wharf, State, Forest, and Boulevard. An article appeared in Dean Kahn’s Dec. 22 column in the Bellingham Herald; prior to that, I sent a photo and a brief notice to David B. Williams’ GeologyWriter.com blog. The 13-foot-tall stack of 4 boulders sits in the new roundabout at the south edge of downtown Bellingham. Shrubs have been planted around the cairn, but they are still spindly and short so it is still approachable on foot.


The lowest two, and the uppermost, boulders are dunite from the Olivine Corporation’s Sven Larsen Quarry on the north flank of the Twin Sisters Range west of Mount Baker. (48° 44.640′ N , 122° 0.345′ W.) The stone second from the top is serpentinite. It also came from the quarry. The stones were supplied by Princess Jade, a stone-supply company in Everson Washington. Get up close enough to see the smooth highlights on the serpentinite boulder, polished by Princess Jade prior to installation. The 8-mile-long Twin Sisters Range is a narrow slab of mantle dunite, among the largest in the world, faulted upward into the crust during plate collisions, and exposed by erosion.

The dunite boulders feature tiny black chromite crystals surrounded by olivine.

The dunite boulders feature tiny black chromite crystals surrounded by olivine.

Dunite is a dense crystalline rock. By definition, it consists of around 90% olivine crystals; the remainderis pyroxene and chromite. Dunite is believed to be the residue left behind when basaltic magma forms in the mantle, typically deep in subduction zones. Water carried into the mantle via the subducted ocean plate (the ‘slab’) lowers the melting point of the mantle, generating basaltic melt. The lower density basalt magma rises upward through the mantle taking lighter minerals such as silica along for the ride, leaving behind the denser minerals – olivine and pyroxene. Serpentinite is a low-temperature metamorphic rock formed when water enters the molecular structure of ultramafic rocks such as dunite. Hydrated olivine becomes a different mineral, serpentine.

Polished highlights on the softer serpentinite boulder.

Polished highlights on the softer serpentinite boulder.

The City of Bellingham had a choice of two designs incorporating the large boulders. The stack won out over the other possibility, scattering the rocks on the ground. Bellingham’s mayor, Kelli Linville, said “The landscaping we chose reflects the natural beauty of our area. Since cairns are traditionally used to help people find their way, a cairn is an appropriate part of the landscape at this important crossroads in our community.” (Bellingham Herald, Dec 22, 2013). According to Sam Shipp, the project engineer at Bellingham’s Public Works Department, the cairn option helps protect drivers from the glare from oncoming headlights and directs drivers’ vision toward other vehicles approaching from the left inside the roundabout, as well as providing an aesthetic component.

Dunite is very dense, about 3.3 grams/cubic cm. Serpentinite is around 2.7 g/cc. Contrast that with basalt (2.8-3 g/cc), andesite (2.5-2.8) and granite 2.6-2.7). The largest stone, the one on the bottom, weighs around 15.5 tons. The two in the middle are 8.5 tons each, and the little one on top is about 3.5 tons. The four stones are held upright by a central steel rod sunk into a concrete base. The project cost $75,000.

OK. “NAME THE STACK” CONTEST! Let’s name that stack o’ rocks! Submit your suggestions via comment and I’ll forward them to the City via my very special confidential connection.

Jamestown S’Klallam tribe acquires Tamanowas Rock

Thanks to alert reader Wendy B. who informs us that the Jamestown S’Klallam Tribe has obtained Tamonowas Rock, near Chimacum. The prominent rock south of Port Townsend last appeared in the pages of this website in November, 2010. According to the tribe, the public will retain access to the reserve, but absolutely no rock climbing will be tolerated on the rock, which is  a sacred place in tribal histories. A trail goes to the top.

Geologically, the rock is  adakitic dacite, a type of rock generated when the  descending oceanic plate melts. Rocks of this type are uncommon in the area. Read the full report in the Olympic Peninsula News. There is some accurate discussion about the geology, and also the role the 150-foot-tall rock has played in history. According to one story, the rock served as a refuge ‘from a flood’. The only logical flood that could impact this area is a tsunami. The most recent geologic evidence for a tsunami in the vicinity is 3000 years old.

I have updated the Tamanowas Rock page to include directions for getting there.

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.

Guided geology field trip offered: Rafting the Owyhee River in Oregon.

Ouzel Outfitters, a river guiding company in Bend, OR, is working with Dr. Kyle House (USGS) to host a 5-day Geology Rafting Field Trip through the lower Owyhee Canyon in south east Oregon.

The trip dates are April 19-23, 2013.

In the deep canyon, carved in rhyolite and basalt. Photo from Ouzel Outfitters.

According to Brian Sykes, proprietor of Ouzel Outfitters, highlights include hiking, photography, natural hot springs, an isolated river canyon, expert geology interpretation, and petroglyphs. Kyle House said this of the Owyhee: “This is possibly the most consistently amazing place that I have ever been lucky enough to work in. I will keep coming back…”.

The Owyhee canyon and the breached lava dams was the site of this year’s Friends of the Pleistocene field trip. The guide book can be downloaded here: https://sites.google.com/site/owyheefop/home/guidebook     (Bonus: you can also download the FOP songbook! Funny songs!)

I’ve included links below for information about this trip. Ouzel Outfitters provides this description of the geologic features on this trip:

“Between Rome and Birch Creek, Oregon, the Owyhee River passes through an astounding landscape born of a long series of geologic calamities. Among these are a series of massive, valley-choking lava flows; a nearly endless array of valley-flanking landslides; and huge flood-generated boulder bars that record the effects of catastrophic floods, landslide-dam failures and even the overflow of an ice-age lake that once sat in the Alvord Desert at the base of Steens Mountain. Over the last 2 million years, the Owyhee Canyon has been invaded by no less than six valley-filling lava flows. The lavas poured down its tributaries and over its canyon rim creating massive dams. Spectacular examples of the lava dams are abundant along this reach of the river, including towering cliffs of lava 100s of meters high; spectacular lava deltas that record the advance of the lava flows into large lakes of their own creation; and a series of ancient riverbeds below each lava flow that chronicle the Owyhee’s inexorable journey to the bottom of its modern gorge. The Owyhee lava dams were immense, some measuring 10s of kilometers in downstream length. At least some of them blocked the river for up to 20,000 years at a time. Once the Owyhee had filled the lakes with sediment and begun to carve its ultimate path around or through the dams, it generated huge landslides as it impinged on new valley walls, often resulting in landslide dams and short-lived lakes that failed catastrophically and moved huge boulders downstream.”

Camp scene on the Owyhee. Photo from Ouzel Outfitters.

Registration is limited to 14 people.  Kyle House and five river guides will give feel of a small personalized tour of fantastic geology, with one-on-one interaction and in-depth presentation.  If you register before the end of December, Ouzel is offering 2012 pricing.  In this case, the price would be $1029.00.

This page gives the quoted description above, plus a link to photos and a video:


This page provides details and reservation information for the field trip:


Rafts on the Owyhee. Photo from Ouzel Outfitters.

An abstract of a paper in the GSA Bulletin describing the lava dams is here:


and a geologic map is here: http://owyheeflotsam.posterous.com/