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    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

Book talk- Geology Underfoot in Western Washington

GUWW cover

Next book presentation by Dave Tucker*:

Camano Island Library

Saturday, April 21: 10:00am – 12:00pm

848 N. Sunrise Blvd., Camano Island, WA 98282

Directions here.

*Yes, alive and well.

Book Presentation in Edmonds September 14

I will be giving a talk about my book, Geology Underfoot in Western Washington on September 14 in Edmonds.

7 PM

Edmonds Senior Center

220 Railroad Ave.

 On the waterfront in Edmonds, directly across the street from the AmTrak station. There is some off-street parking at the Center, and there is elevator access. This is the montly meeting of the Ice Age floods Institute. Free and open to the public.

I will have copies for sale, $24. Also copies of the cover poster, $15. See you there!



New book: Geology of the San Juan Islands

San Juan Islands geologist Ned Brown brings us a wonderful new geology guide- just in time for holiday gifts.

Ned Brown's Geology of the San Juan Islands. Chuckanut Editions, 2014

Ned Brown’s Geology of the San Juan Islands. Chuckanut Editions, 2014

Geology of the San Juan Islands is a full color guide to the geology of these beautiful islands. The book is written for the geophile of all stripes. It is the best, easiest-to-understand explanation of San Juan geology I have seen, and I urge you to spend $19 and get your own copy right now.

Ned Brown is an emeritus professor in the Western Washington University Geology Department. He has been working in the islands for decades. The complex geology of the archipelago has long inspired and exasperated geologists. Ned’s book describes the remarkable tectonic history that has repeatedly brought together unrelated rocks from around the Pacific and stacked them against each other during subduction. His color photos and detailed diagrams explain the processes and evolution of each of the rock units clearly. The book also explains how he and others have come up with this most current interpretation of San Juan Islands geologic history, by mapping rock units and faults, dating zircon crystals in the rocks, identifying fossils and correlating these with the ancient areas where these creatures lived.  Ned tells you just where to go to see the best outcrops, including all the photo locations. Among the more amazing ideas he throws out is the possible origin of the oldest rocks in the  350- to 500-million year old Turtleback Complex on Orcas Island. The gabbro and granitic rocks, once intruded deep in the crust,  may have originally intruded deep in the crust….in northern Europe! This was during the time of the supercontinent Rodinia.

The book is self-published through the Chuckanut Editions imprint of Village Books in Bellingham. The book is not yet available. Go buy a copy in the store, or write Village Books and ask them to please make the book available for on-line orders.Dave Tucker


Rock Trail, Larrabee State Park

Bud and the thin beds at the overhang.

Thin beds in the Chuckanut Formation along the Rock Trail.

I will post a full geologic guide to the new Rock Trail when the trail is formally opened on April 26th. An email subscription to this blog will deliver the news to you directly. In the meantime, please enjoy other Chuckanut area geology descriptions on my blog.

Fragrance Lake

Raptor Ridge

Oyster Dome

Clayton Beach– a layer of volcanic ash preserved in the Chuckanut Formation

A full listing of localities I describe is here. For a primer on Chuckanut geology, visit this page.

Dave Tucker

200,000 hit milepost reached; New page about uplift.

Migmatite at Diablo Overlook, Highway 20. This is a mix of metamorphic gneiss and intruding igneous dikes. My frien d Klayton for scale, lower left. Photo copyright Dave Tucker

Migmatite at Diablo Overlook, Highway 20. This is a mix of metamorphic gneiss and intruding igneous dikes. My friend Klayton for scale, lower left. Photo copyright Dave Tucker

This website reached 200,000 hits on the afternoon of January 10th. The article on quartzite did it. To celebrate, I dusted off an old draft and have posted it. This one is in the ‘Geology Basics’ section, and is about how rocks deep in the crust are uplifted to reach the surface. It is an excerpt from a chapter in the book, Geology Underfoot in Western Washington that deals with the Skagit Gneiss, which was at one time as much as 18 miles (30 km) deep in the crust. Read it here.

Geology guide to Fragrance Lake Trail (Larrabee State Park)

The Christmas Girls had just finished decorating all the sign posts as I pulled into the parking lot. Very festive! Click to enlarge.

The Christmas Girls had just finished decorating all the sign posts as I pulled into the parking lot. Very festive! Click to enlarge.

I’ve written up a geology guide to the popular Fragrance Lake trail. You’ll find it here. Even if the hike is mostly in glacial till, there are interesting stones in it, and the Chuckanut cliffs are always worth a peak. I do some armwaving about the origin of the big cliffs above the lake, too.

Pillow lava localities in Washington- a new series on Northwest Geology Field Trips

Doing what comes naturally with pillowed lava. Grand Coulee near Lake Lenore.

A page explaining the origin of pillow lava has been added (link). There will be five field trips to diffferent places where pillow structures can be observed in Washington. The first of these has been posted here, to see pillows along the Heart O’ the Hills Road in Olympic National Park.

The other planned pillow field trips are:

  • On the beach at the foot of North Cape Lighthouse, Cape Disappointment State Park (near Ilwaco)
  • Richardson, on Lopez Island
  • Sand Hollow, along the Columbia across from Vantage
  • The Manashtash Viewpoint on I-82, south of Ellensburg

Notices will go out to website subscribers as I get them written. If you wish to send photos and descriptions from other places, please have it! Send writeups to:

send email here

How to trust science reporting: Is it peer reviewed? How about stuff on this blog?

The WWU Geology Department has posted a policy statement on science publishing. The department’s stated position says:

“The Geology Faculty at WWU believes that all science must be subjected to rigorous peer review and publication before it becomes worthy of serious discussion. We do not support publication of non-peer-reviewed scientific results in the general media. A brief guide to peer review is available at Sense About Science.”

The linked guide is titled “I Don’t Know What to Believe”. The article is about how to make sense of science reporting, whether in the popular media or on scientific websites (or places purporting to be ‘scientific’, such as creationist and global warming denialist sites). The article explains how peer review works.

The guide touches very briefly on abstracts submitted to scientific conferences. These are generally NOT peer-reviewed, although some aspects of the science reported in abstracts may have been reviewed. These are simply summaries of scientific investigation to date, and intended to initiate discussion with interested peers at the conference prior to writing a full journal submission. An abstract is NOT to be taken as a published paper. Anyone may submit an abstract to a conference; sometimes unscrupulous people then claim to the undiscerning public that they have ‘published a paper’.

A significant exception is any abstract submitted to a conference with even a single USGS scientist as a coauthor, regardless of where that person’s name occurs in the list of authors. This also applies to other ‘non-journal’ papers such as GSA, Northwest Geological Society, or any other organization’s field trip guides. All of the Mount Baker abstracts on which I am an author, for instance, have been reviewed by USGS scientists, as is the field guide to Mount Baker deposits in the Baker River valley published in the 2007 GSA field trip guide. For a list of these abstracts, scroll down on the abstract page at the MBVRC home page ; look for abstracts under “Tucker, D.S.” or “Scott, K.M.”, a USGS colleague co-authoring all my Baker work to date.

The  “I Don’t Know What to Believe” guide also a short comment about how peer-review journals are funded.

All the science I describe on this website has been, to some degree at least, peer-reviewed, and references are given at the end of each field trip. If there is no reference provided, then my text is a paraphrase of reviewed science. An exception would be the physical description of some very recent phenomenon. An example is the field trip up Silver Creek to see effects of the debris flows back in 2009. These trips are principally a report of observed events and deposits, rather than claiming to be some new scientific discovery.

While you are visiting the Geology Department’s “Position Statements” page, note that the faculty accept that human-induced climate change is a fact. This is in direct opposition to the outspoken views about ‘global cooling’ and statements about the ‘hoax of global warming’ made by Dr. D.J. Easterbrook (professor emeritus on the faculty). Dr. Easterbrook’s name is not specifically mentioned in the position statement.

My own policy on this website will be to clearly state what science appearing on my website has been peer-reviewed, what is simply my interpretation (or that of other scientists), and what is a general consensus in the geologic community.



Geology basics- a new page on the website

By popular request, I’ve begun a new page on the website, GEOLOGY BASICS, accessed from a tab at the top of each page. I’ll try not to turn this into a textbook-length effort. The first explanation has been added, which discusses the concepts of strike and dip of sedimentary layers, with illustrations and links to trips where you can see good examples.

I’ll add to this page sporadically. If I gloss over a concept in a posted field trip that you think deserves inclusion in these primers, send a comment and I’ll see what I can do.

Take me to the new page!