About this website

The website is written by Dave Tucker. I am a research associate at Western Washington University’s geology department. While my research focuses primarily on volcanic rocks and events at Mount Baker and the nearby Hannegan caldera, this website is not limited to volcanic geology.

Larrabee Park Rock Trail and Chuckanut Geology– please visit this page on my website.

This is intended to be a cooperative effort. Please use a comment to contact me about submitting field trips you want to write, or places you’d like to know more about.

This website will post illustrated geology field trips to sites where you can lay hands on cool geology, or get good overviews of the geology of northwest Washington and southwestern British Columbia. Some field trips will be along roads, some will require hiking, and there will be trips for demented folks like me who don’t mind a little, or a lot, of cross country travel– bushwhacking, scrambling, stream crossing, glacier crossing, and the like.

Hope you enjoy it. If you do, please forward the URL to others you know who might like it. Word of mouth is the #1 means of publicizing this website. Also, please sign up for an email subscription, so you will know when new trips have been posted.

This page suggests a way to PRINT paper copies of the field trips on this website.

Some of the most popular items in this website:

The Lake Stevens erratic, among the largest known in the US, discovered in June 2011.

Diatryma, the giant flightless bird and its 50 million-year-old fossil footprints.

Your EMAIL ADDRESS is NEVER used by this blog or wordpress.com for ANY purpose except to contact you about updates to this blog, or about events of interest related to northwest geology.

You can contact me at this cleverly disguised email address:

dtchico   at    gmail   dot   com.

This helps keep spammers out of my inbox.

Dave Tucker
Bellingham, Washington

80 Responses

  1. Thanks for putting the field trip info together!!!
    I’m in Port Townsend so am most able to join trips in the area, but am happy to go further afield as time allows. Not a geologist…just a well informed lover of rocks.
    I look forward to emails from you about trips.

    • Leslie,
      Well, I don’t offer actual field trips. I’ve been thinking of doing this as a little side business. Is their interest from others out there to get together for a guided trip to interesting geo-sites?

    • As an older Geology student (older than dirt) – and recently returned to college to finish up my BS and go for a MS with intentions of getting into Petroleum Geology (I used to work in the oil patch as a field technician) – I would be very interested if you decide to offer some guided trips to geology sites!


    • Dave. Hello. I love this site especially the glacier boulders site. Big one near Martha lake also. Please keep me posted. Thanks glenn

    • Just got your …Underfoot… book for Christmas. Started at the back with Calderas And Columns, since we were just there last July. Great illustrations! I’d be willing to sign up for some of your tours, if you decide to do that. We’re not in Washington yet, but hope to relocate to the B’ham area next Spring/Summer – somewhere a bit higher than the pending tsunami will reach, and away from slide-prone slopes ;^)

      Happy New Year to you and yours!

  2. I’m a Bellinghamster without a car, and personally, I’d love a chance to relive the field trips of my college days.

    • Elizabeth,
      Try the geology field trips I lead through the WWU Academy for Lifelong Learning. Also, I teach for North Cascades Institute. Dave

  3. I have been trying to find this location for the last few weeks since a friend of mine, Rand Jack, mentioned it to me. Said a friend of his told him about it. Are you that friend? Anyway, I went up the road you speak of but didn’t know of the diving off spot, I had just started investigating the spurs. Last week, I went up the bike trail up the other side of the creek and could see the landslide. I marked the coords on my gpsr and was going to attempt the road approach again. Now, with your help, I am heading up in just a few minutes. Thank you!

  4. And I guess I should say which hike…Racehorse Falls Landslide.

  5. Hi – I’m a recently retired Drama teacher with no science background who now finds herself in a Geology 101 class at Whatcom Community College: picture the grey-haired woman in the back row amongst all the 18-year-olds. It’s absolutely fascinating. Go figure. As for the guided tours, I’m very interested. (Though the more challenging hiking may be beyond my skills.) Please keep me informed if you decide to go forward with this idea, and thank you for the website!

    • Glad you like the website, Kitty. Easy to picture the woman you describe– one of the great things about WCC. When I went back to college to start my graduate degree a decade ago, I started at Whatcom with remedial algebra classes. I was not the oldest in that class, and often not in the following ‘higher math’, chemistry, or physics classes. The age disparity became REALLY big when I transferred to WWU for the Masters program. Hang in there, never stop learning. You might be interested in courses taught through WWU’s Academy for Lifelong Learning. Find them on the web. I teach geology through them. Dave (another gray hair).

  6. I just want to say thank you for putting all the work in to create this website. It was great that the Herald saw fit to write about it!

    I moved up to Toad Lake from California five years ago and finding your blog brings me an entirely new way to appreciate the area where we live. I am a complete novice about geology, but I’m still the little girl with the rocks in her pockets, even though I am the same age, more or less, as you are. Can’t wait to read more!

    Thanks again,

    Susanne Freeborn

    • Susanne, glad you liked the website. We won’t discuss our ages, thank you. Subscribe, if you didn’t already. Dave
      [PS] Don’t overfill your pockets with rocks! Your pants could fall down!

  7. Hi Dave,
    I am an old prospector and enjoy bushwhacking, scrambling, stream crossing and old mines 🙂

    Also, please sign me up for an email subscription, so I will know when new trips have been posted.

    Thanks in advance

    • Kris-
      Sounds like you know how to fun! You need to sign yourself up for updates by clicking the ‘subscribe’ link at the upper left of the website. Dave

  8. Hi Dave…interesting idea! Will check in regularly.

    Kyle House
    WWU geology class of 1989

  9. Dave,

    I’m a humble youngster taking PNW Geology through WAOL, more specifically through Ralph Dawes at Wenatchee Valley College, and stumbled upon your site as I look for supplementary information regarding my term project on Wildcat Cove, off of Chuckanut Drive. I just moved to Bellingham from Clarkston, Washington and am fascinated by the distinctly different landscape. I’m even contemplating going to WWU for a degree in Geology to teach Earth Science. Who knows? I’m in love with this. Thanks for creating your website!

    • Samantha,
      I very strongly recommend WWU for Earth Science Education. There are a couple of really great geology profs there who doubel in the ed department, Scott Linneman and Sue DeBari. Glad you like the website. Let us know what you find out about Wildcat Cove!

  10. Hi Dave
    What about the big rock on the beach in Whiterock BC?
    The town is named after it. Also I know of two glacial erratics on the shoreline; on the SW corner of Jones Island, and on the south shore of Orcas Island, east of Grindstone Harbor.
    I just subscribed. Glad to see you doing well.
    Yours for the OBU,

  11. Can you tell me why, when climbing up a mountain of serpentine rock on the Ingalls Lake trail, when you get to the pass, you then look across a valley that is a straight as a string, to Mt Stuart, which is as far as I know pure granite? In the same area(Teanaway), when you climb up eastward out of Bean Creek Basin, the ridgetop is decorated by what looks to me like pillow basalts. There must be some story here!

    • Peg,
      Thanks for commenting. There is indeed a story here. I have never done any field work in the Teanaway, though I have climbed there plenty. The Stuart batholith intrudes the older rocks in this area. The contact doesn’t actually follow the ‘straight as a string ‘ Ingalls valley, however- some of the Stuart rock is south of Ingalls Creek as well. The geologic map is found at http://pubs.usgs.gov/imap/i1311/wengmp.pdf go to the upper left corner to find the Stuart area [pink units].
      The serpentinized rocks are a small mantle slice, similar to the Twin Sisters west of Mount Baker. I don’t know about the specific rocks above Bean Creek, don’t recall being there or seeing these. But the Ingalls area has been refered to as an ophiolite, a section through the crust that includes the uppermost mantle rocks as well as some seafloor basalt. Maybe that is the story you saw. Since it is the Cascades, there are likely to be the usual complications to the simple explanation. There is a 2008 paper about the area, a link to the abstract is here.

  12. Hi Dave,
    Just stumbled upon your website while getting to know the Misch collection at North Cascades National Park.
    Am voting an emphatic YES! on the idea of guided trips. In the meantime, thanks for the field trip guide! *As soon as the road opens, I’m going to the Pollywog Agmatite*
    Your Fellow Rock Nerd,

  13. Dave
    I am interested in your guided field trips but for some reason when I tried to subscribe it said I was not activated?? Any ideas?

    • DT replies:
      I have no idea what is meant by ‘not connected’. Can any other readers help with this?
      Pat’s comment showed up as a notification in my email inbox, as all comments do, for me to approve or not. When I clicked on ‘approve’ it showed up on the website, as normally occurs.

  14. Scott Babcock recommended this site to our class this evening. It looks like you have done a very good job. Can’t wait to enjoy the “field trips”. I want to be a geologist when I grow up (shhhhhh don’t tell anyone but I am 46).

  15. The Evergreen State College Geology Club thanks you for this awesome website!

    • Thanks, Greener geologists!
      Glad you like the website! Please tell me about any of the trips you have made. How about writing about a place you enjoy visiting that is not on the website? This website is intended to be collaborative.

  16. I have been a rock hounder for the last 25 years and just recently added prospecting to the list of things to learn about.
    I love to soak up any geology info I can get
    Thanks Nate

  17. Very interesting. I will keep checking back!
    Do you know anything about the ‘boulder’ just northeast of Tonasket, on the way to Republic?

    – Lane

    • Lane,
      I’ve never seen this split rock. Looks metamorphic. Maybe some other reader has a clue.

    • Ah yes, I know that rock. It is located about 5.82 miles NW of Tonasket on the Havillah Road, NOT on the way to Republic, which is Hwy. 20 (unless you want to go to Republic in a very roundabout route, which, of course, would be fun! But this rock is not off Hwy 20.). It’s on the west side of the road, about 0.4 miles north of the junction with Fancher Rd. UTM: Zone 11, E327825.00 m, N5401960.00 m. It’s on the edge of what appears to be a glacial lakebed (Fancher Flats). There are many large mostly metamorphic “erratics” all along various lake level benches around this flat, and they are not very rounded, so hadn’t traveled far. (Are they erratics if they are of the same material as local bedrock? There’s a classic argument! There isn’t basalt in this area of glaciation.) Perhaps they were floated in on big chunks of ice and ended up on shore lines as the lake receded. And receded. And receded.

  18. I live in East Wenatchee and am trying to identify the strata of rocks along the Columbia River specifically the Rock Island Grade. Do you have info on this area?

    • Kahni,
      The Rock Island Grade climbs up the east wall of the Columbia [I found it on Google Earth]. I don’t know the area specifically, but looking at it in GE, I see that the lowest switchbacks climb up an alluvial fan, then enters what must be Columbia River basalt up to the top. There isn’t enough detail to see if there are any of the sedimentary interbeds of the Ellensburg Formation- these are lake and alluvial deposits laid down on top of lava flows prior to being buried by the next flow. I don’t know of a geologic reference for the area. If there are any specific outcrops you are curious about, you are welcome to take some photos and email them to me. I’ll try to help identify what you are seeing.

  19. Dave, I stumbled across your blog and see that you are planning to come to Ilwaco soon. I have a motel close to that site and hope you come by and get a room while you are here. You look familiar and I think I know you from Bellingham.

    • Gale,
      Thanks for the invite, but no plans to come soon. I will be posting an online field trip to the pillows at Cape Disappointment State Park later today.
      If any website readers stay at Gale’s motel, the 101 Haciendas in Ilwaco, please send me a report.

  20. Interesting site. I will have to do some exploring here in the future especially on this topic of possibly guided geologic field trips? That sounds quite the interesting possibility. I am taking my 9 year old son to a talk about Kilimanjaro tomorrow at WCC. He wants to hear from someone who has “climbed a huge mountain.” My son and I also went fossil hunting somewheres up on Chuckanut. We happen to find what we believe to be a bone of some sort, still encrusted in hardened “stuff” with fossil leaves. Don’t know if you can post pictures or not…no worries 🙂

    My name is Chad, went to Whatcom for a bit but the reason I am commenting is because there is a place in Big Lake WA called Haystack Mountain. We used to call it the Devils Rock Gardens in high school.

    Just curious if you have ever been there or could possibly even offer a geologic explanation or perhaps even point me towards a study of this particular place. What happened there to create such a stunningly odd place? (or perhaps its not odd at all?)

    About 15 years ago I recall somebody giving me the terminology to describe this place. I also recall them saying there were only 2 or 3 sites like it in all of North America. I also recall researching those assumptions and blowing them apart. Essentially, I cannot recall and google is not helping 🙂

    ps. there is a particular rocky place on Haystack, I am not sure if the name Haystack mountain refers to this exact location or if it refers to the entire mountain. The rocky place: it looks like something took thousands of rocks the size of cars and houses and through them up in the air and they landed how they may…

    • Thanks for writing, Chad. I hope to write a field guide to Walker Valley Boulder Field (aka Devil’s Gardens) soon.

  21. Ahh, I did a little search on your site and found the piece named:

    The HIgh Dome of Bald Mountain, and Big Rock, too.

    A quick look at the directions has me thinking this is exactly the place. Going to play a little chess, can’t wait to read the article.

  22. Great site,

    Hey all,

    Something I noticed, and maybe you already know about this, but at 3rd beach in La Push WA. you can find Poppy Jasper. I believe it is a relatively rare stone in the Western US. A friend of mine has/had a Poppy Jasper mine near Gilroy California which is how I recognized the poppy pebbles.

    I’m a old world stone mason, wavedesigstoneworks.com you have to type it into the address bar it’s closed to the search engines.

    Anyway I find stone intriguing as I harvest from the source almost all of the stone I use. I go on rock quarry exploratory trips across the West every summer and have been cataloging some interesting finds.

    I have two questions.

    I. Have you ever noticed any flagstone formations in WA, Wilkeson and Tenino are to well consolidated to break into planes? I would love to find a local greener source, possibly a USFS public quarry or even on private land.

    II. What is the green stone found in erratics, my god it is the hardest stone I have ever used, completely useless, melts diamond blades and turns over chisel edges and fractures carbide?

    Morrisons gravel in Port Orchard always has a large pile of huge erratic boulders (acres) that are harvested in a gravel operation. I have seen genuine granite, quality marble and a whole range of amazing rocks of interesting origins. You might want to check it out.

    Thanks a lot I enjoyed your informative site immensely and will return as time allows.


    • Tony,
      Afraid I don’t know much about collectable stones. You asked two questions:
      1. I don’t know where to reliably find usable flagstones for the taking. Maybe another reader does.
      2. The green stone of the erratics is, well, called ‘greenstone’. It is a low grade metamorphic rock, usually lava or tuff with a basaltic or andesitic composition that has been subjected to some heat and more pressure, usually due to subduction. I am surprised to hear it is so hard, as the parent rocks are not unusually used in stone carving, and the chemistry and mineral composition of the metamorphic daughter rocks is similar; some of the minerals in the greenstone should be softer, even, on Moh’s scale.

  23. Regarding the split rock in the images from Lane, Dave is certainly correct in that it appears to be metamorphic rock. From the pictures and the general location, I would further say that it is Swakane gneiss, a high-grade metamorphic rock that extensively outcrops in the area. Not knowing the precise surroundings for this site, it could either be a boulder that fell from bedrock and later split, probably due to ice wedging along a weakness (the foliation plane), or possibly it was carried by ice (not exactly a classic erratic if it is derived from local bedrock) and deposited when the ice melted. With nothing definitive for scale next to it, it is hard to tell from the images how large this is, but it “looks big”!

  24. I am not a trained geologist but I love seeing the
    monumental stories of the relentless forces of nature in the stones.

  25. Hello Dave,
    I’ve always wondered about the large “mounds”/irregularities to the East of I-5 between the Skagit and Samish rivers… They’re pretty hard to miss. How did they form, and what exactly are they?

    • That is a good topic to pursue in a field trip, Carston. I’ll be heading down that way to put together a post about those ‘knobs’. They are bedrock knobs rising above the flat ‘sea’ of alluvium from the Skagit and earlier glacial outwash coming from Pleistocene ice receding to the north. Stay tuned.

  26. Great blog Dave! Being a product of the WWU geol dept I enjoy both the content and the names that crop up. I just spent a day at Cape Disapointment. The best part of the day was walking out to the surf during low tide (5am-ish), and disapearing into the fog for a couple of hours. Photographing the pillow ballasts at sunrise was awesome and I found myself looking for core holes and paleomagnetists. Keep up the great work!

  27. Thanks for the great blog. Not sure if this is reasonable or not, but I thought I’d post a question here and see if I had any luck. I’m looking for formations of honeycomb limestone or “texas holey rock” somewhere in the northwest. Their existence up here has been rumored, but I’m not sure where to look. Any ideas?

  28. My daughter is majoring in geology at Eastern Washington University in Cheney. We live in Spokane. Any ideas for trips in our area?

    • Marian,
      Invest in a copy of Bjornstad and Kiver’s “On the Trail of the Ice Age Floods- the Northern Reaches”. This book has a number of field guides to the Spokane-Cheney area. I’m sure faculty members at CWU can provide your daughter with field trip guides, too.

    • Contact the local chapter of the Ice Age Floods Institute: http://www.iafi.org/cheney-spokane.html They organize wonderful field trips, mostly oriented toward the Big Floods, but hey, it’s a start. It’s all geology.

  29. I moved to Camano Island, WA recently and took a long beach walk today on the west side of the island starting at Madrona beach going north. I’ve been sort of fascinated by these big greenish rocks and took some pics today of a really unusual one but there are several quite large ones. They seem to look a bit like the Jackass rocks on your site but I’m not any expert on rocks, I just like them. Happy to send pics if you’d like them and describe, show you or snap some shots of others.

  30. Live in Central Wa- love the geology of the Missoula floods and basalt rock formations- always up for a new hike

  31. Thank you for some trip tips and interesting info about volcanic stuff. It will need some time to get thru it all 🙂 Regards from european uni 🙂

  32. What a treasure this blog is– I can hardly wait to start reading posts. Found you through the Falcon Guide “Modern Rockhounding … Handbook”.

    • Darika, Thanks for your enthusiasm. I’d better get going on another field trip post! I didn’t konw the wegsite was listed in the rockhounding guide book.

  33. Dave: Thanks for your great website and your book Geology Underfoot. Since purchasing the book 6 months ago, my wife and I have visited many of the 22 sites described. They are all good, and form a wonderful cross-section of the rich geology found in western Washington. Chapter 14 – A tour of Downtown Seattle Building Stone was an eye-opener; what a rich variety of stone from around the world. We now pay closer attention to the stone in every building we encounter.

  34. I would like to thank you for including a watermark in your images. I needed an image of pillow basalt on the WA seashore just now and it makes it very convenient when you do that. I am from WA and I miss the geology (although I do like SW geology a bit better) so when I was referencing NW geology and had no good pics myself, I used one of yours and I am thankful that I didn’t have to include a reference, even though I also mentioned it anyways because, well heck, you guys are good! Thanks again.
    -Eric Beckstead

  35. When is your next field trip :)…

    Thank you
    Kimberly Vanpetten

    • Hello Kimberly, Thanks for writing. I don’t actually offer in-person field trips. This blog has languished for a while but I intend to post more self-guided trips soon. Please stay tuned. Dave Tucker

  36. Interested party that lives in Snohomish. Now headed to see Lake Stevens erratic – msybe after thi gs quit sliding dince you said it is on a ravine. Love your book.

  37. There is a large boulder on squak mountain that I suspect is an erratic (just based on similarities with the Fantastic Erratic on Cougar Mountain (a couple of miles away)). How might I test the hypothesis?

    • Tom,
      Erratics by definition have a different lithology from the bedrock they sit on. So, a granite boulder sitting on sandstone is an erratic- and vice versa. I don’t know what type of rock the boulder you mention is, nor do I know what the bedrock is in that location. So to test your hypothesis, you would need to find a geologic map for Squak Mountain [sorry I don’t know where that is]. I haven’t personally been to the Fantastic Erratic so I don’t know the lithology of that boulder. If you need help from me, I’d suggest 1] send a good quality close up of a cleaned surface of the erratic, and 2] send me the location of Squak Mountain.

  38. I have discovered a new hobby of trying to visit as many of these erratics as I can. I’m just wondering if this is still an active web site. I have a question.

  39. I followed the link you provided to the UW glacial erratic site, and can’t find any real content there. It claims to have an interactive map and a list but I can’t find them. Is that site still supported? (This is the link I am talking about: https://waglacialerratics.ess.washington.edu/ )

  40. The webpage is loading a lot of advertising. I can’t control the content of said ads and I find some inappropriate to all G rated audiences. I thought this was a educational page.

    • Thanks for your comment months ago on ads on my site. The only way I can control those is to buy the URL from WordPress. I don’t see the ads when I open the website on my own computer so was unaware. Will look into that.

  41. Excited to have just discovered this sight. I am a Bellingham man all my life. Can’t wait to take a field trip or 10. Geology is my new vice after far to many years of less productive vices, if you will. Geology is saving my life!

    • Jonathan,
      I don’t actually lead in person field tirps, in case that is your expectation. These are all self-guided geology trips.

  42. Dave
    Amazing how one can make discoveries on the internet. I came across your incredible site tonight, quite by accident.
    I’m in Centralia, WA, but live in Tacoma.
    My birthday is 09/18, I’m seventy-two today and finding your site, with all its information, is the most incredible birthday gift. I’m ecstatic. Can’t wait for my daughter to wake up so we can start planning.
    I saw the comment section and had to express my excitement. You are so well informed about the area, and make it easy to find local sites. I’m on a fixed income, so really, to now know there are sites near by to explore, touch and find history, WOW.!
    I know now I have to live another thirty or so years. A lot of exploring and finding to do.
    Thank you again

  43. We have quite a large erratic on our property in Edmonds but can’t find that it has been added to the list of erratics in Snohomish county. I would like to know more about the age and composition of it. Do you know of anyone I can contact that might be helpful with this?

  44. Hello,
    Any advice on where to find agates in whatcom county? Thanks.

    • Kierstin, I’d hunt around on any coastal beach. I’ve found plenty there. No specific recommendations for a location, as all the agates here were transported southward out of eastern BC during the last glacial advance.

  45. Hey Dave, I retired from teaching so hve been pretty lazy but was looking for the Fossil Creek do it yourself trip. It used to be on this site but no more. Any chance of getting it? Would like to pass it on to my daughter who it not a teacher.

    • Hello Roger, Congrats on retirement. Fossil Creek? There is a Fossil Creek in the Nooksack Formation along the Baker Highway accessed by the Church Mountain Road, but II haven’t written up a trip there; it’s not at all inspiring. Are you thinking of Racehorse Creek? I have a lot of stuff about fossils there.

  46. Thank you for responding. Yes, I believe that is the location. I did use your instructions before and have several specimens from the site. After rereading my last text, it should have said, my daughter, who I took with me when we went last time, is now a teacher!

  47. I enjoy all the posts on glacial erratics. I have a particular interest in near-shore erratics around the Salish Sea. Is anyone familiar with this landform just north of Snee-Oosh Point on Fidalgo Island?


    It’s over 15 feet high, sits isolated on a beach, and has a characteristic erratic shape (rounded and undercut around the base), but I don’t know what additional evidence a professional geologist would look for to clinch it as an erratic.

    I have beach-level pictures I took of it, if that would help. Thanks.

    • Hello Jeff, Thanks for posting the comment. Looking at the link you sent, I’m pretty sure this must be an erratic. Is their public access? Bear in mind there are uncounted numbers of these big rocks all over the Salish lowlands. To verify that this big boulder is an erratic, a geologist would need to examine it and see that it is different from the local bedrock, indicating transport from somewhere else. There does appear to be a smidgeon of bedrock exposed on the point just a few feet to the south, so such a comparison could be simple. Go take a look yourself! If you look at this place on Google Earth and zoom in you will see a photo taken of a bunch of young men standing on this rock. At a guess, I’d say it is granitic, which is most definitely ‘not from here’.

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