Saturday, September 20, 2014

Haul Road Repaired Below Ross Dam

I got a brief view of the rock slide below Ross Dam at the upper end of Diablo Lake diablo-lake-rock-slide. The slide area was repaired by knocking down the loose stuff and remaining precarious rock and rerouting the access road outward a bit.  
 
I happened to be taking in the view when the supply barge was pulling up to the upper end of the lake.

The logistics of managing the Ross Dam power house and dam present some challenges. The same applies to management of the lake above the dam. The road referred to as the Haul Road is not connected to any other roads. The narrow steep sided gorge limits access. Equipment, vehicles and materials must be barged up Diablo Lake downstream of Ross Dam and then transported on the Haul Road up to the dam or to Ross Lake above the dam. 

Wednesday, September 17, 2014

The Other Ice-Age Flood: Bonneville Flood


The highway through Lewiston, Idaho passes by a gravel cut slope with a retaining wall at its base to catch material that ravels off the slope. The cut slope is a deposit from an ice-age flood. But this flood was not derived from the rapid draining of ice-age glacial Lake Missoula. Instead this thick deposit of gravel was derived from a massive ice age flood when Lake Bonneville in northern Utah overflowed into the Snake River drainage in southern Idaho approximately 15,000 years ago. When Lake Bonneville over topped the pass at Red Rock, the resulting flow of water rapidly down cut a channel draining the lake down 350 feet.

The flood greatly altered the Snake River and areas along the river in Idaho and left a series of large gravel bars and terraces within and downstream of Hells Canyon including deposits along the lower Snake River in Washington State. It likely left a mark all the way down the Columbia River to the Pacific Ocean; however, the much more intense repeated ice age floods from glacial Lake Missoula obliterated most if no all the evidence. The Bonneville flood deposits a bit upstream of Lewiston were deposited over back water sediments from the Missoula Floods and in turn later Missoula Floods deposited backwater sediments above the Bonneville deposits. Tom Foster has a nice write up http://iceagefloods.blogspot.com/2010_05_01_archive.html with some great images from the Lewiston to Pittsburgh Landing area of the Snake River.

    

Tuesday, September 16, 2014

Grande Ronde Basalts at the Grand Ronde

The southeast corner of Washington State provides an opportunity to see the source area of some of the great flood basalt flows that cover much of eastern Washington. While there are plenty of impressive basalt cliffs and canyons in Washington State, the canyon land topography of the Hells Canyon and Grande Ronde River Canyons as well as tributaries gives an even better impression of  thickness of the basalt flows.

View down Rattlesnake Creek to the Grande Ronde River.

Basalt lined slopes of Rattlesnake Creek

A feeder dike can be seen just west of the Highway 129 bridge across the Grande Ronde River. Schuster's 1993 map of the area marks the dike as Grande Ronde basalt. 

Feeder dike of basalt cutting through older basalt flows in Grande Ronde canyon

The Grande Ronde basalts are the most extensive flows by area and by volume These flows extend all the way to the Spokane area and all the way to the ocean in southwest Washington. The Grand Ronde flood basalts make up somewhere on the order of 85 percent of the volume of the Columbia River Basalt Group.

Camp and Ross provide one take on the massive out pourings of basalt from the mantle plume camp.   The Grande Ronde basalt came out of some of the earlier dikes in the Chief Joseph dike swarm in northeast Oregon and southeast Washington. The name Chief Joseph is derived from the fact the area of the basalt feeder dikes is within Chief Joseph's beloved homeland before he and his group of Nez Perce were forced off their land.

 


Saturday, September 13, 2014

Porch Poodles, ISIL or ISIS and Scotland

I have been meandering about the Northwest so part of my landscape observations have been overprinted by more than the usual dose of news.  A political observer in my community once described the individuals making constant critical comments "porch poodles" - insistent that something is happening and something must be done but running away from taking any real action themselves. 

This bit of satire from Karl reMarks sums up my impression of the yak fest on ISIS or ISIL and Scotland.

Finally, and drawing from our collective experience as Middle Experts, we must stress that the US should not and must not continue its policy of non-intervention in the Scottish independence question. We must do something. Things must be done. There is a necessity for the doing of things. It’s also the point at which we normally ask the requisite rhetorical question near the end of the end: should we allow Scotland to exist as a small oil-rich country? (Like, do we need another Qatar now?) President Obama must avoid this by arming the Protestants. Or the Catholics.

The entire article is HERE.

More Washington Landscape stuff later.
 

Wednesday, September 10, 2014

Desolation

I took a trip up Desolation Peak as part of a group adventure with the North Cascades Learning Center. Desolation gained some fame from one its fire look outs - Jack Kerouac spent one summer watching for fires from the look out and wrote Desolation Angels from that period.
 
One of leaders was a former lookout Gerry Cook. It was great fun to be in the lookout with him and current lookout, Daniel.  
 
 
Some clouds were about while loafing on the summit, but we had a fine view of the other Skagit River delta where the river flows into Ross Lake near the U.S - Canadian border.
 
 
In the other direction Ross Lake looked fjord-like in its deep mountain valley.
 
Hozameen, a crazy steep peak to the north wore a hat all day long.




Daniel has a tradition of taking pictures of his guests.
The next day those clouds and their moisture became less stable and we picked up Daniel's message on the radio about lightning to the east.

Most of my field time and camping is not social and I do much of my field work alone. I very much enjoyed my temporary tribe and our adventures.
 


Wednesday, September 3, 2014

Silts and Slope Failures at Discovery Bay

Subtle variation in the geologic units on a bluff can make a big difference in how slopes fail. At this bluff in Discovery Bay, west of Port Townsend, the main driver is erosion at the base of the bluff by wave action. But how the bluff fails is important in terms assessing risk to sites above the slope.
 
A few notes on this view of the bluff. The trees on the slopes above the bare bluff are generally mature Douglas fir. Its a harsh growing environment so most of these trees are on the order of 80 years or older. The lower slope is pre last glacial period silts, clays and sands that are compact and resistant to erosion and stand vertical. The slopes above vertical bluff sections are far from vertical suggesting looser material. Indeed those slopes are underlain by mostly sand and gravel.  Note also the thick wedges of landslide debris at the base of the bluff. The one behind the boats is from a slide that took place in 1998. The one on the far left that covers the cliff face took place two years ago. 
 
 Closer view shows vertical fractures in the silt layers on the steep bluff
 
Chunks of silt spalled off the bluff face as brittle blocks 
 
But the same hard, brittle blocks turn to mush when wet. The wetting of the silt unit along the upper part of the steep bluff appears to be playing a role in upper bluff slope failures.

What had been a hard, dense, over-consolidated silt has dilated into weak silt incapable of supporting the units above. As this silt and clay collapses and falls apart the slope above of loose sand and gravel then pours down the slope. The process of the clay and silt units changing from hard compact material to highly fractured material and then soft mush is a feature of many larger landslide complexes. At this particular site the scale of the slides is relatively small perhaps because the zone of altered silts is fairly thin.  

Sunday, August 31, 2014

One Offset in the Dabob Bay Fault Zone

Last year the Washington State Department of Natural Resources published the Geologic map of the the Seabeck and Pouslbo 7.5-minute Quadrangles, Kitsap and Jefferson Counties, Washington (Polenz and others 2013). At a personal level it has been great to have this map as it covers an area where I have done a fair number of projects. The map confirms a number of observations I have made, but also clarifies some features that were well beyond the scope of what I was specifically working on. The map also includes some big pictures interpretations that reflects the progressive deeper understanding of the Puget Sound basin and the glacial history of the area. The pamphlet provides detailed explanations to how specific units have been interpreted and notes there is still some debate regarding specifics. This map is one of a series of very good maps that the DNR has put out and given my experience in the area. 

Perhaps the most exciting part of this map is the designation of a fault zone cutting across the Toandos Peninsula on the west side of Hood Canal. This zone had been suspected for some time as some deformation had already been noted by previous workers in the area (Carson, 1975). 

Polenz and others (2013) noted a fault offset that Carson (1975) had noted on the southeast corner of the map shown below measuring the off set trend as northwest with a steep dip at 85 degrees to the southwest. I had made a similar observation a few years ago and have a couple of pictures of the feature.   

Portion of the Polenz (2013) map across the south central Toandos 

Small offsets along silt and sand units

Off set location

There is a bit of a change regarding slope stability north and south of this particular off set. Just to the north there are a series of deep-seated landslides associated with some lake sediments that are not present to the south of this off set location.

There are not a lot of definitive fault off set locations exposed within the younger glacial and interglacial sediments. Polenz (2013) found an even more definitive off set site to the northwest. A future post as I recently visited that site.