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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

Google Earth Washington Geology Map program

Google Earth screen shot showing Skagit County, Washington, geology

Google Earth screen shot showing Skagit County, Washington, geology. Click to enlarge any image. The Eocene Rhyolite place mark is my own.

Google Earth (GE, download it here) can be a great tool for looking at landforms. Washington State’s Department of Geology and Earth Resources has prepared a set of 1:100,000 geologic map overlays for the state’s counties. Find them here. Scroll down to the very bottom of the webpage to find “Google earth 1:100,000 scale Surface Geology 3d overlays” . Download the kmz file, which automatically opens in Google Earth. The various geologic layers are listed in GE’s ‘Places’ menu. You can click the boxes to show, or hide, whichever aspect you are interested in. For instance, the default map units are opaque, and you can see no landscape through them. You can adjust the transparency of the overlay, or even hide the map colors (under the ‘geologic units’ submenu) so all you see are the welter of contacts. A tutorial video by DNR on YouTube explains usage of the Google Earth geology overlay. This uses the Whatcom county kmz file as an example.

The transparency slider.

Unit transparency slider: ‘Geologic units’ is highlighted, then click the blue box next to the magnifying lens, and tweak the slider.

The tutorial isn’t very clear on adjusting transparency, so I’ll go over that first. First, click the ‘geologic units’ box in the menu, then the blueish icon next to the magnifying glass at the bottom of the menu. Use your mouse to adjust the slider until you are happy, or at least reasonably satisfied.

GE Skagit geology, with unit polygons turned off. Lines are contacts and faults. Unit names remain.

GE Skagit geology, with unit polygons turned off. Lines are contacts and faults. Unit names remain.

GE Skagit county showing only occurences of Twin Sisters Dunite.

GE Skagit county showing only occurrences of Twin Sisters Dunite.

You may choose to use the menu to show only faults, or only unit labels, or only certain units. However, there may be a TON of map polygons associated with each unit, and each isolated occurrence of, say,

‘Darrington phyllite’ has its own box in the places menu. I’m still getting the hang of it. It is worthwhile to download one county’s geology .kmz file, and zoom out so the entire county is visible. Then you can click the various units listed in the expanded menu to see just what map unit, and where, that unit box belongs to. If you click on the name of a unit on the GE map screen, a balloon pops up with more, or less, information on the unit (see the figure below). Perhaps there will be only a tiny bit of information that is of little use, or maybe you’ll get lucky and get unit name, age, and even a reference. You can always rename units to make it easier to locate them in the places menu. Suppose you are interested in Darrington phyllite but only in the Blanchard Mountain area. You can find one of the mapped phyllite polygons on the GE image, click on the colored map polygon to see which label in the menu at left is highlighted, then rename that menu item ‘ Darrington SE Blanchard’ or whatever sort of personal label makes sense for your interests. You want to set aside some free time to play around with this program.

Burlington Hill (see page here on NW Geo FT blogs) with a unit clicked for info.

Burlington Hill (see page here on NW Geo FT blogs) with a unit clicked for info. Not all of the unit callouts will have this much information.

This is definitely a useful reconnaissance tool. These .kmz overlays take up a fair amount of space, so when you open GE you’ll need to be patient as they all load. The more county GIS layers you load into your GE program, the more slowly GE will open. You can always choose not to keep them in your GE Places menu, and access the maps from the DNR website each time instead. But then you have to tell GE not to save the overlay in the temporary places list when you close GE. Suit yourself. I use this tool a lot to help plan out field trips, so I’m the sort of person who would leave it loaded on GE in my computer.

Columnar jointing in Washington

By Dave Tucker  September 29, 2010

The most recent post on the entertaining Magma Cum Laude blog, by Jessica Ball [aka ‘Tuff Cookie’] states:

“Perhaps we should submit a request for a Columnar Jointing Week to someone in Washington.” Maybe she means a Presidential dictum for ‘National Columnar Jointing Week’.

Okay, well, I’m “someone in Washington”– State, that is. I can’t issue any dicta whatsoever, so will reinterpret her ‘challenge’ to show off some photos of columns from Washington State. This won’t be a field trip on the Northwest Geology Field Trips website just yet. I’ll work these various stories and photos into future field trips. Click any photo to enlarge it.

Pinus Lake andesite, Mount Baker (Hildreth and others, 2003). I already wrote up a field trip to this orphan andesite lava, with the spectacular columns rising above the Mount Baker Highway. Here’s the photo again.

The 300-foot-thick Pinus Lake lava towers 600' above the Baker Highway east of Nooksack Falls. Click to enlarge any photo

Here are some more andesite columns, in the Table Mountain lava flows of Heather Meadows near Mount Baker. This flow is similar in age to that of Pinus Plateau, around 300,000 years old. It erupted from a vent on Ptarmigan Ridge, and forms the inverted topography of Table Mountain between Mount Baker and Mount Shuksan.

Stubby, 1-meter-wide columns in Table Mountain andesite along WA 542 below the Mount Baker Ski Area.

The Table Mountain lava (Hildreth and others, 2003) has stubby columns at the lowest elevation exposures, shown above. However, higher up, the lava has much skinnier columns, suggestive of cooling in contact with ice. Just above the Heather Meadows Visitor Center (USFS) are these wonderful columns right along the highway. They cooled against the steep valley wall. The radiating columns show that the cooling front was spreading out into the interior of the flow.

Cooling fractures define these columns in the Table Mountain andesite. The radiate into the interior of the flow from the outer edge of the lava.

And how about these ice contact columns? These are in the 70,000 year old Portals andesite on the north wall of Rainbow Creek at Mount Baker.

Crazy divergent glassy columns in a flow that cooled in contact with glacial ice 70,000 years ago, Mount Baker volcano.

Now, lest you think I am completely Baker-centric, here are some columns in a dacite lava near White Pass, south of Mount Rainier. These are in the Clear Fork Cowlitz River, and can be seen from a small interpretive site along US Highway 12 west of White Pass. The glaciated flow is around 650,000 years old (Pringle, 2008).

Clear Fork dacite, US 12, 2.3 miles east of the junction with WA 123. Columns are 650 feet high!

And then there is Beacon Rock, the 57,000-year-old (Evarts and others, 2009) eroded plug along the Columbia River just west of Bonneville Dam. The colonnaded south face of the rock rises 850′ above the river. The cinder cone that once surrounded this basaltic andesite plug was eroded by the catastrophic Missoula Floods.

Big columns on the south face of Beacon Rock, seen from the boat launch just to the west along Washington 205.

Of course, the Columbia River Basalts provide quintessential examples of columns in Washington State. Here are some in the Grand Coulee, on the west shore of Lenore Lake (US 97).

Several stacked flows in the Columbia River basalts, Grand Coulee.

Here’s a detail of the wildly diverging columns in the lower right of the photo above:

As thick lava cools, cooling fronts migrate into the interior of the flow. These columns are bounded by fractures which grow inward from cooling into the hotter part of the flow.

The Columbia River Basalts flowed out the ancestral Columbia River and radiated into southwestern Washington, too. Here are some columns in a quarry near Rainbow Falls State Park, which are west of Chehalis on US 12.

CRB columns in the Chehalis River valley, Western Washington.

So, I’ve done my part to answer Tuff Cookie’s challenge. How about…Oregon? Or is it a matter of ‘seen some, you’ve seen ’em all?”


Evarts, R. C., Conway, R. M., Fleck, R. J., and Hagstrom, J. T., 2009, The Boring Volcanic Field of the Portland-Vancouver area, Oregon and Washington: tectonically anomalous forearc volcanism in an urban setting. In Volcanoes to Vineyards: Geologic Field Trips through the Dynamic Landscape of the Pacific Northwest, ed. J. E. O’Connor and others, 253-270. Boulder, Colo.: Geological Society of America.

Hildreth, W., Fierstein, J., and Lanphere, M., 2003, Eruptive history and chronology fo the Mount Baker Volcanic Field, Washington: Geological Society of America Bulletin v. 115     p.729-764.

Pringle, P., 2008, Roadside Geology of Mount Rainier National Park and Vicinity. Washington Division of Geology and Earth Resources, Information Circular 107.

Honeycomb weathering in the Chuckanut

A field trip to Larrabee State park, Governor Lister Cliffs, and a brief description of how honeycomb weathering produces ‘tafoni’ structures is now available.

Racehorse Creek landslide field trip

A hiking field trip to the complex deep-seated Racehorse Creek landslide of January 7, 2009 is now available for your geological pleasure.

Blowers Bluff geologic field trip added

A geological field trip to the fabulous glacial and interglacial deposits at Blowers Bluff on Whidbey Island is now up. You can find it at


The field trip will be found by going to “The Field Trips”, then “Pleistocene Glacial Stratigraphy on Whidbey Island”, then the trip. YOu can also find the earlier trip to Useless Bay and Double Bluff there.

A visit to the Coupeville erratic on Whidbey

Check out this 30-foot-high monster!

The 30-foot-tall Coupeville erratic sits in front of a house and an apartment complex.