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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 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

 

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 is flowing again.

Dan McShane has been keeping an eye on the river gage on the Stilliguamish below the landslide. His latest post shows that the river is no longer backing up behind the landslide dam. Dan includes a graph from the river gage. I’ve copied his screen capture below- click to enlarge. You can see that discharge [= flow measured in cubic feet per second] dropped instantaneously just after noon on 3/22, from 2000 cfs to 900, and continued to decline down to 700 cfs until Sunday at around 3 PM.  Then the level of the impounded river had risen enough to begin overtopping the low point on the slide surface and began to flow downstream again. The last data point on the graph is from Monday at about 6 PM, and flow seems to have stabilized. You can track the discharge yourself at the gage website.

Stilliguamish gage data. Click to enlarge.

Stilliguamish gage data. Click to enlarge.

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.

Landslide diverts Nooksack River near Deming, Washington

View up river from top of Clay Banks in a snowstorm. Landslide toe in river is at right center. Photo by D. Tucker. Click to enlarge photos.

View up river from top of Clay Banks in a snowstorm. Landslide toe in river is at right center. Photo by D. Tucker. Click to enlarge photos.

A landslide about 1 AM February 21 diverted the Nooksack River. The slide occurred at the infamous ‘Clay Banks’ about 1.8 miles upstream of the Baker Highway bridge at Nugents Corner, near Deming. I’m passing along the essentials from Dan McShane’s Washington Landscapes blog. I visited the site this morning with geologists Scott Linneman (WWU) and Eric Grossman (USGS), and have posted a few photos and a new Google Earth map. The river has cut through the low-relief landslide toe, and there is now no impoundment of the river. According to residents we spoke with there was another large landslide a couple (?) of weeks ago. They said they could hear a deep rumbling when the February 21 slide released.

T'photo of slide toe in river. The river has cut around the toe, and also through its body. Photo by D. Tucker

T’photo of slide toe in river. The river has cut around the toe, and also through its body. Photo by D. Tucker

Annotated Google Earth screen capture. D. Tucker

Annotated Google Earth screen capture. Blue lines indicate river channel as of AM, Feb. 22, 2014. D. Tucker

Access to all viewpoints is on various private properties, which are amply posted ‘No Trespassing’, etc, etc. You can’t see anything from anywhere without trespassing. Watch for possible updates. We’ll make and effort to get more information and better photos soon.

The Clay Banks consist of Pleistocene glacial till sitting on top of a very permeable sand layer, which in turn sits on top of older glacial till. It is very prone to sliding and has destroyed two houses that were built in the forest several hundred yards back of the top of the bluff in the late 1980s or early 1990s.

John Thompson's photo from the gravel bar, Feb. 21, 2014.

John Thompson’s photo from the gravel bar, Feb. 21, 2014.

This house was gradually undercut and has slid off the brink of the Clay Banks. Photo by Dave Tucker, Feb. 2013.

This house was gradually undercut and has slid off the brink of the Clay Banks. Photo by Dave Tucker, Feb. 2013.

Dan’s post:

Nooksack River Temporarily Blocked by Landslide

Via a network of folks that pay attention to the Nooksack River:. The flow on the river at the Cedarville gage took a brief plunge last night from 2,300 cfs to 400 cfs.
 

At Lynden 11 miles downstream a less substantive, but still sharp drop and recovery took place. Lynden Public works reported a sharp increase in river turbidity.

USGS staff noted the dip in the discharge and Whatcom Flood Division confirmed a large landslide at the Clay Banks had blocked the current main channel and deflected the river back to an older channel.

Clay Banks landslide can be seen at bottom center
Topo of Nooksack River and Clay Bank

…As can be seen the river has been up against the steep bluff in the past. However, the frequency and duration of the river being against the steep bluff has been enhanced by the construction of a high rip rap levee on the opposite bank preventing the natural meander of the river.

1998
Note the slide on lower left and rock levee on the opposite upstream bank

Posted by at 9:35 PM

Racehorse Landslide Fossil Beds- big rockfall; trail is brushed out

George Mustoe (WWU Geology Department) visited the famous Chuckanut fossils in the Racehorse Fossil Beds a few days ago. He sends a report  on trail access. (If you aren’t familiar with this place up the Nooksack east of Bellingham, this is the site of the 2009 landslide that exposed the 11-inch-wide foot prints of the 300 pound, 7-foot-tall flightless bird Diatryma, and a host of other animal tracks and plant fossils from the 55-million-year-old Chuckanut Formation. Directions follow George’s trail report. There are many reports on this website about the fossils and the landslide. Go to the older posts and pages.

George’s report:

The largest of the blocks in the 2013 rockfall.

The largest of the blocks in the 2013 rockfall. Click to enlarge any image.

A few days ago I went to Racehorse slide with Gary Coye. We took some gardening tools, and trimmed branches that had grown up along the way trail. There’s presently a clear trail route all they way up from the parking area to the ridge crest, at least until the branches grow back. As for driving, the gravel road is the best I’ve ever seen it in terms of being smooth. This is the first time I’ve been to the slide this year, and I was surprised to see the big rockfall on the scarp face that  must have happened this past winter. I’m attaching some photos, Some of the biggest rocks came from the top edge of the cliff, and carried down intact vegetation. You can see Gary standing on one of the largest blocks, and the scar on the face where the rockfall originated.

The 2013 rock fall came from the upper end of the vertical landslide scarp.

The 2013 rock fall came from the upper end of the vertical landslide scarp.

How to get there:

Google Earth scren capture, looking south

Google Earth scren capture, looking south

These directions are current as of June 23, 2013. Drive the Mount Baker Highway east from I-5 in Bellingham 17 miles to the junction with Mosquito Lake Road. Turn south (right). Cross the North Fork Nooksack, and turn left on the North Fork Road. Set your odometer to 0.0 here. This paved road eventually becomes gravel. You will notice some big blocks and hummocky terrain along the road at about 2.2 miles, the hallmarks of landslides. These are the deposit of a large prehistoric landslide that reached the Nooksack, dwarfing the 2009 slide. The hillsides above  have slid multiple times since the end of the last glacial period, and the mountain itself is called ‘Slide Mountain’. Follow the mainline to a major junction immediately before the bridge across Racehorse Creek, 4.1 miles. Turn right on this gravel logging road, and begin climbing. In about 0.2 mile, you may note a trailhead on the left, with parking on the right. This goes through the woods a couple of hundred yards to the rubble-choked course of Racehorse Creek. A quick trip out this trail reaches the stream. You can walk up-stream a few hundred yards to the lovely multi-tiered water fall.

Continue up the road beyond the trailhead. You will pass  a few side roads, but stay on the main line. Turn sharp left  5.1 miles from Mosquito Lake Road. This left turn is just after a white ’1′ painted on a tall tree on the right, in a clump of woods. The road switchbacks up; pass a couple of minor semi-overgrown spurs to the left.  and is blocked at a fork 5.7 miles from Mosquito Lake Road. 48° 52.295’N, 122° 7.455’W. Walk up the left fork, blocked by deep ditches and mounds of gravel; a trail passes around the right side of these obstacles. Walk up the road 100 yards to the next switchback swinging to the right, next to a high pile of logs. Here is where you take a path into the clearcut, just as the road swings right. The elevation is approximately 1450′, and there is a nice view out to Kendall and the North Fork from here. The entire field trip is on Washington State Department of Natural Resources timber lands. Total driving time from Bellingham is less than an hour. Please consider taking some pruners with you to help keep the trail open, especially where it leaves the road.

The trail reaches the now overgrown landslide debris field in a hundred yards. Here is where to start looking for plant fossils in the broken shards of rock. This is a small ‘overspill’ of the January 2009 landslide. The slide scarp is up the slope and out of site beyond the skyline ridge crest. Pick your way up the ;landslide slope around fallen trees, rock blocks and brush to the skyline, about 200 feet higher. Now you can see the rock face of the scarp to the right, and the upper part of the deposit in the basin below you. The main body of the slide went to the left (east) and down into Racehorse Creek.

Middle Fork Nooksack debris flows- another one, and an update

The Middle Fork has cut 10 m through the May 31 debris flow. Click to enlarge.

The Middle Fork has cut 10 m through the May 31 debris flow. Click to enlarge.

There is a description of ongoing dramatic changes to the new debris flow deposits in the Middle Fork Nooksack over on the MBVRC blog. There has been a second debris flow, on June 6th.

Debris flow update: http://mbvrc.wordpress.com/2013/06/12/more-debris-flows-in-middle-fork/

Comparative YouTube videos. June 9th  video shows major changes in only four days: http://www.youtube.com/watch?v=8cepN93zOY8

Compare with the June 5th YouTube video: http://www.youtube.com/watch?v=4vVJPPwLgwM

More on Middle Fork Nooksack debris flow

By Dave Tucker  June 7, 2013

Photo by John Scurlock. Explanation on the link to today's MBVRC blog post.

Photo by John Scurlock. Explanation on the link to today’s MBVRC blog post.

The source of the debris flow in the Middle Fork Nooksack River is now believed to be a large landslide rather than a glacial outburst flood. This is based on new aerial photos provided by John Scurlock and Steph Abegg. The updated post is on the MBVRC blog.

There is video I made when I visited the deposits two days ago. See it here on YouTube. Shows the extent of the debris flow deposit at the Ridley Creek ford.

And another YouTube video shows a volcanic debris flow [a.k.a. ‘lahar’] raging down a valley in Indonesia. It is probably similar to the Middle Fork flow, except considerably smaller.

There will be another visit to the deposit Sunday AM early by a geologic team to begin serious study of the deposits and to try to begin estimating volume, velocity and other parameters of the May 31 debris flow. There will probably be an update posted on the MBVRC blog, so if you don’t already subscribe to it, consider doing so.

Debris flow video- MUST SEE

If you like watching video of dynamic geologic events, watch this one!

It shows a debris flow in a channel pulsing through the Austrian mountain town of Virgen following heavy rain in late August, 2012, and is incredible. Watch for large floating boulders, carried along on the dense flow of sediment. This is one of the top debris flow videos ever made, on a par with the one made by Kevin Scott of the USGS when he was working in the Jangjia Ravine in China.

The Austrian video comes our way from the Landslide Blog, always worth checking out.

MBVRC Geology field trip offered, North Nooksack River

Columnar andesite of the Pinus Lake lava flow towers above the Baker Highway east of Nooksack Falls. Click to enlarge the photo

Here’s a reminder to sign up for the Mount Baker Volcano Research Center field trip to volcanic rocks and landslides in the North Fork Nooksack River (Whatcom County) on August 8th. The cost is $75, which includes a guide and van transportation from Bellingham. Proceeds support the MBVRC research fund. Van seats are limited, so reserve your seat quickly.

The trip will visit the towering and beautiful lava columns of the Pinus Lake lava above Nooksack Falls, Nooksack Falls themselves, the huge Church Mountain Landslide that swept the site of the town of Glacier only years, and other local geology sites depending on interest and time.

The trip will be led by Whatcom Community College geologist Doug McKeever. For a full description, photos, and sign up information, please visit the MBVRC blog post about the field trip.

Reserve a seat now by sending an email to:

This is not a link

Please include ‘field trip’ in the subject line. Subscribe to this or the MBVRC blog to be the first to hear of more geology trips offered later this summer and fall.

Cheers,

Dave Tucker