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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

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.

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.

Snohomish and Tacoma Geology Underfoot Book talks

A reminder that I will be in Snohomish this Saturday, Feb. 20, and in Tacoma next Thursday, Feb. 25, to talk about Geology Underfoot in Western Washington.

SNOHOMISH Saturday February 20th, 2 PM, Sno-Isle Public Library, 311 Maple Ave., Snohomish, WA

TACOMA Thursday February 25 Kings Book Store, 218 St Helens Ave Tacoma, WA. 7 PM http://www.kingsbookstore.com/event/2016-02

 

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!

Dave

 

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

Link to Ridley Creek Trail geology guide:

https://nwgeology.wordpress.com/the-fieldtrips/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

Washington interactive geology map

I get a lot of emails asking about on-line geologic maps. The Washington State Department of Natural Resources has a great resource. It is the Washington Interactive Geology Map. It allows you to select map scales, map background (topographic? street map? terrain?) and the type of geology you are interested in (faults? surface geology? tsunami inundation zones? landslide? volcanic vents?). You can play with scales and move around on a map of the entire state. The portal is here, which connects you to several interactive maps: http://www.dnr.wa.gov/ResearchScience/Topics/GeosciencesData/Pages/geology_portal.aspx

If you choose the Interactive geology map, you end up here: https://fortress.wa.gov/dnr/geology/?Theme=wigm

The menu lets you select lots of features to turn on or off. You have to play with it a bit to get it really

screen capture of a portion of the interactive geology map.

screen capture of a portion of the interactive geology map. Click to enlarge.

figured out, but it isn’t difficult. The figure above shows the screen set for western Whatcom County. In this menu I selected ‘surface geology’, 1:24,000 and 1:100,000 scale geologic map overlays. 1:24,000 scale maps are only available for some areas, and show up in the image as an area with denser information; an example is in the center, and lower left. You can zoom in on those for more detailed geology. You can turn text labels for geologic units on or off to reduce clutter. The more data you request, the slower the system is to load. I also clicked the box for ‘seismogenic features’, which turned on the blue dashed diagonal faults on the left edge of the screen.

Interactive map showing mapped faults in wesern Whatcom County.

Interactive map showing mapped faults in wesern Whatcom County. Click to enlarge.

This figure shows a much simplified view of seismogenic features only, in the same area. There are several fault strands in the Kendall area at center, as well as the same three faults between Gooseberry Point and Blaine. All the other information is turned off for clarity.

REQUEST TO READERS. If you experiment with any of the other interactive maps on the portal page (tsunami inundation zones, coal mine inventory map, natural hazards, seismic scenarios, etc. please consider writing a comment below about how useful you found it.

Stillaguamish Landslide- Geologic Perspectives

Interpretation of landslide scarp on LiDAR image, by Dan McShane.

Interpretation of landslide scarp on LiDAR image, by Dan McShane. Click to enlarge.

Dan McShane has written some geologic perspectives about Saturday’s landslide into the Stillaguamish River. Dan is a consulting geologist based in Bellingham and author of ‘Washington Landscapes’ blog, and has some great insights into the geology and history of the slide area. Rather than trying to rewrite his excellent reports, I’ll just provide the links. It is not the first landslide in this location. In my view, it  is a tragedy that people are permitted to live in this location.

 

Dan’s Initial report:

http://washingtonlandscape.blogspot.com/2014/03/arm-waving-notes-on-stilliguamish.html

Geologic background:

http://washingtonlandscape.blogspot.com/2014/03/geology-of-silliguamish-blocking-slide.html

LiDAR images and slide history.

http://washingtonlandscape.blogspot.com/2014/03/aerial-history-and-lidar-of.html

Stay tuned for more posts from Dan. Consider subscribing to his blog.

 

Nooksack River landslide near Deming- Update #2

Red line marks scarp of Feb 21 landslide. A later, undated slide is outlined in green. The second slide send brown soil over the top of the earlier clayey slide.

Red line marks scarp of Feb 21 landslide. A later, undated slide is outlined in green. The second slide sent brown soil over the top of the earlier clayey slide. Click to enlarge any image.

Thursday I visited the toe of the February 21 Clay Banks landslide on the Nooksack River, in company with Scott Linneman (landslide geomorphologist at WWU Geology) and John Thompson, a geologist with Whatcom County Natural Resources. If you haven’t been following this story, please visit Dan McShane’s blog post for the background to the story including some fine maps and photos, and my original post from February 22, the day after the landslide. Dan has also posted a great set of old maps and LiDAR showing changes at the Clay Banks as the river changes position. The landslide occurred just at midnight Friday February 21; you can see the sudden radical, short-lived drop in the river discharge graph below (recorded at the river gage a mile downstream at Cedarville). Click link to annotated You Tube video.

The Nooksack River gage at Cedarville (Nugents Corner) recorded a brief but sharp drop in discharge while the landslide dammed the river.

The Nooksack River gage at Cedarville (Nugents Corner) recorded a very brief but sharp drop in discharge (from ~2500 to 400 cfs) while the landslide dammed the river. Click to enlarge.

Annotated Google Earth image, with corrected location of 2-21 landslide and new river channel at the toe. Click o enlarge any image.

Annotated Google Earth image, with corrected location of 2-21 landslide and new river channel at the toe. Click to enlarge any image.

The Clay Banks are a steep bluff of Pleistocene glacial clay around 100 feet high on the south side of the river about 1.8 river miles upstream of the Nugents Corner bridge. The landslide bit deeply into only the upper half of the bluff, leaving a prominent bench hanging above the river. There is landslide debris on the bench, but most of it appears to have flowed over the bench, down the bottom of the bluff and into the river.

Shaky split log spans a side channel.

Shaky split log spans a side channel.

We crossed a shaky foot log across a narrow side channel to get to the big gravel bar on the north side of the river, and then walked 350 yards to the river side directly opposite the landslide toe. The landslide began in a layer of glacial clay a few meters above a prominent alluvial bed called the Deming Sand. If there is a stratigraphic layer at this level in the Clay Banks that contributed to this landslide it was not apparent using a high power spotting scope.

The toe of the landslide consists of large blocks of clay.

The toe of the landslide consists of large blocks of clay.

The river is still ponded against the landslide toe which protrudes into the river for 200 feet or so from the south bank. The river has cut through the outermost edge of the landslide toe. The river drains the partial impoundment by racing through a 60-foot-wide (19 m, measured with a laser range finder) gap. We couldn’t measure the river depth, but know it was 5 feet right up against the bank we were standing on, and 10 feet or more may be a reasonable guess. The landslide toe consists of car-sized, or maybe even garage-sized, clay blocks, and rests on the surface of a gravel bar; the bar gravel is exposed beneath the debris. At the time of the landslide, the river was closely beneath the high bluff, and the gravel bar we now see beneath the toe was part of the one we were on. The river then cut a new channel around the outer edge of the deposit, isolating the bar gravel beneath the toe from the gravel bar on the north side of the new channel. We found a single, angular clay block lying on the north side side of the channel, and a number of rounded ones. We figure the angular one (see photo below) was tossed laterally out of the landslide toe. It hadn’t been rounded by river flow, so is almost certainly right where it landed at around 12AM Friday 2-21-2014. You can see the same block in Dan McShane’s post, though when he visited the river bank was a few feet furthe away. This block is direct evidence that the river is continuing to cut outward and remove the bar on the north shore. This block will probably tumble into the river in the next few days.

Angular clay block marks extreme outer margin of the landslide toe. River has cut a new channel between this block and the rest of the landslide.

Angular clay block marks extreme outer margin of the landslide toe. River has cut a new channel between this block and the rest of the landslide.

The surface of the landslide toe is covered with large clay blocks. These sit on topo of a pre-landslide gravel bar.

The surface of the landslide toe is covered with large clay blocks. These sit on topo of a pre-landslide gravel bar.

The river makes an end run around the toe, and then cuts sharply south and runs directly into  the base of the bluff below the landslide. This is certainly undercutting the base of the Clay Bank, setting the stage for another collapse, perhaps involving the entire bluff height rather than the upper half.

Among our observations is that there has been a second, much smaller landslide in the same place. We don’t know when this occurred, but it sent darker material over the bank and down onto the southern margin of the Feb 21 toe. Compare the photo taken by Dan McShane on the morning of Feb 22 with the one I took today (Feb 27). The center of the 12-hour old scarp in his photos is now deeper where the 2-?? landslide collapsed. Also in the photos, note the toppled trees that rode the slide over bank.

The Clay Banks extend another 1/4 mile or so upriver and 1/2 mile downriver from the 2-21 landslide. Earth movements have been happening here at various scales for decades, and are likely to continue long into the future.

ACCESS NOTE: All access is over private land, so you are dependent on reports from authorized visitors. Sorry. Don’t even try to get there yourself. It is difficult to see the Clay Banks scarp from anywhere on the north side of the river. You may get a glimpse from the Deming Road somewhere in the first half mile after it branches off Mount Baker Highway a bit east of Nugents Corner. However, you will be 7/10 of a mile away, and for sure can’t see the river or the landslide toe.

Citizen geology- new page added to Northwest Geology Field Trips

This new page directs readers to projects they can participate in, usually as volunteers with a minimum of geologic experience. Go to the Citizen Geology page.

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.