Bioturbation of Upper Soil in Eastern Washington Range Land

Whenever I visit a burned over area of eastern Washington range land I am impressed with the bioturbation as it shows up a bit better with the surface of the ground covered with blackened plant remains. Within days there are piles of freshly dug silts covering the landscape. A good reminder of how much soil turnover takes place in the upper soil horizon. These critters will do a very good job of disrupting carbon horizons and volcanic ash layers. 

 

 

Trip Out Ediz Hook, Port Angels

I previously posted a short note on sediment and the Elwha Dams removal elwha-sediment-and-shoreline. For shoreline sediment folks the dam removal is a very exciting opportunity. Sediment sinks behind dams have significant impacts to coastal shoreline processes all over the world. The net shoreline drift at the Elwha is decidedly to the east towards Port Angeles and Ediz Hook. 

 

 

Ediz Hook with Port Angeles

 

The Hook forms an amazing wide and protected harbor as it effectively blocks ocean waves and swells coming in the Strait of Juan de Fuca from the west. I was out in Port Angeles this week and had a bit of early morning time to head out onto the Hook. A well worthwhile drive or run or bike ride. There is some good shoreline processes to observe, but plenty of other stuff as well including birds, a large feral cat population and up close look at a paper mill.

 

The initial part of a trip onto the Hook passes right through a paper mill.

 

Nippon Paper Industries USA

Bear in mind that seventy years ago the Strait of Juan de Fuca was lined with long range cannons to avoid a Japanese attack as a reminder of how fast change can happen.

While the big picture of Ediz Hook is shoreline drift and sediment from the Elwha, there are smaller scale shoreline processes. Just before the paper mill a brackish tidal inlet has just enough fetch to erode the unprotected east shore of the inlet.
 

The road out to the hook passes between the buildings and drive yards of the paper mill. Speed limit is 15 mph and there is a stop sign and speed bumps.

Paper rolls in a warehouse

A bit beyond the warehouse is a shoreline restoration site where treated wood and concrete were removed and the shoreline was lined with logs and new imported clean gravel. The idea was to improve habitat and to stop erosion towards the road. The harbor waters are large enough that erosion does take place on the inside of the Hook. And when big waves hit the outside of the Hook and over top the spit, the over wash can cause erosion as well if no sediment is transported over the rock break water lining the outer edge of the Hook. 

The project was completed about one and a half years ago so the vegetation is just getting established. The site is likely being monitored to see what works and what does not. I will say I like the bright yellow flowers blooming in mid November.

The north side of the Hook is where the high energy big waves work against the spit. With the loss of sediment from the Elwha this land form which was already rather thin has become susceptible to erosion. The morning I was there the water was calm and the tide was out.

It will be a long time before sediment from the Elwha River begins rebuilding the spit again. And even then, keeping such an ephemeral land form locked in place will likely require continued engineering and maintenance. And given the high energy environment, it will require big rocks.
 

New rocks for keeping up the harbor protection

 

The view across the harbor to Port Angeles with the Olympic Mountains behind

Deer Doing Bonsai

With few predators, if any, deer in the San Juan Islands have increased in number such that they have a noticeable impact on the landscape. Homo sapiens are not the only environmental influence in the anthropocene. The deer on Blakely Island, like deer elsewhere in the San Juans and perhaps the suburbs, have taken up bonsai pruning. 

Western red cedar

Stunted Douglas fir

The Yakima River Changes Course

The views from the Hinge (View from the Hinge and picnic-at-hinge-in-horse-heaven-hills) also provide a view of the altering of the route of the Yakima River from the ice age floods. 

View of lower Yakima River valley and Benton City

The puff of steam on the horizon is the large nuclear power plant at Hanford

I liked this alignment of a turn right sign with the Yakima River below making a left turn.

 Prior to the ice age flood the Yakima turned right instead of left at this location.

Ice-age flood waters filled the former Yakima River valley to the right with sediment

After the flood waters exited the river followed a new coarse to the left instead of to the right

View of Badger Coulee, the former lower Yakima River valley 

DEM showing the turn in the river

Digging Holes for Geology and Engineering

Bob and I did a little subsurface investigation in Seattle for a foundation excavation. We had the advantage of a good project manager for the developer that noted that there was a good exposure of the subsurface within a deeper part of the foundation of the existing building on the site and came up with a scheme for excavating the foundation. Our job was to simply verify the soil types and develop the geometry of the excavation in a manner that would be safe for the workers and would not put the neighboring building and property at risk. 

The area is mapped as glacial till and I had seen enough of the local till in that neighborhood to suggest we could likely reach undisturbed very hard till with hand tools. Saved a bit of money and time as indeed we had success. Hard glacial till may be lousy for gardens and stormwater drainage, but it does have some geotechnical advantages.   

Bob measures and tests the hard unweathered glacial till in our first pit

The second pit found very hard till at less than 1.5 feet.

One last note: Happy Veteran's Day to Bob and all our veterans.

Wading For Geology

Sometimes its a bit of a challenge to time shoreline bluff visits with the tides and other projects. Wednesday I had a breakfast talk to give and then headed to couple of shore projects on the Olympic Peninsula side of the Salish Sea. The second shore site was a little short on beach sediment.

 

The lack of beach material was the result of a couple factors. First, the high eroding bluffs at this shore reach are predominantly clays which are readily transported off. The lag of cobbles is not enough to build a beach. Secondly, a reach of low bank has been heavily armored with rock bulk heads for many years cutting off a significant sediment source. Low banks are often overlooked as beach sediment sources, but they do erode and do supply sediment. Indeed a low eroding shoreline bank will recede much faster than a high steep bluff simply because the volume of erosion to cause recession of the shore is so much less.

Combine a sediment starved shore reach and throw in the landslides with trees and brush there is nothing more to it - time to get wet.

All in all a good work out with the added resistance to walking and weight of wet pants and boots. And really not so bad this early in the fall as the water is still not too cold.

Eureka Flat: a Coulee Formed by Wind?

Eureka Flat is an anomalous flat stretch of land across the southwest Palouse. This flat stretch appears to be related to wind blowing through Wallula Gap. 

 

Low spots along the Cascade Range are areas with significant wind movement and as such have been the hot spots for wind energy development new-landscapes-defined-by-wind. A low west of Ellensburg and the Columbia River valley through the Cascade Range have been the focus wind energy projects. The Horse Heaven Hills along the north side of the Columbia form a barrier that focuses the wind coming up the Columbia along the ridge tops and hence the summit Ridge of the Horse Heavens from south of Kennewick to Walla Walla is lined with wind turbines. 

There is a break in the Horse Heaven ridge at Wallula Gap and besides to Columbia River moving through the gap wind passes through the gap as well.

View from the upper slopes of Wallula Gap to the northeast

 

Just upstream of the gap the Walla Walla River joins the Columbia and a bit further up stream from there the Snake River flows into the Columbia. In the early fur trading period a trading post "fort" was built at the gap. The site operated as a fur trading post from the 1818 to 1857 by the North West Company and then the Hudson Bay Company. The fort was an important station in the early days of U.S. control of the territory and early accounts from that period focused on the wind. While the fort was strategically located for trade purposes, the wind made it rather uncomfortable. 

 

In those days there was more than just wind. The wind had lots of material to blow. Yearly flooding on the Columbia River left huge sand bars and piles of silts that would be exposed to the wind blowing through the gap. The flood sediments would be blown through the fort area to points northeast into the Palouse Hills. What was left behind were lag deposits of coarse sand and gravel.

 

The stronger winds blowing through the gap appears to have shaped the land to the northwest leaving what appears to be a long divot extending from Wallula Gap nearly to the Tucannon River through the southwest part of the Palouse Hills. A portion of this area is called Eureka Flats.

 

DEM of Eureka Flat

Aerial view of upper Eureka Flat (USGS)

 

Driving through this section of the southwest Palouse the sudden flatness of the area is an anomaly compared to the more rolling hills of the Palouse. The area appears to be a broad coulee, but it is not associated with any flood water path. It has been postulated that flood waters may have over topped the upper end of the Eureka Flat valley, but the upper end of the Eureka Flat valley is likely too high to have been over topped. So I am inclined to lean toward a wind explanation for this subtle landform.  

 

West edge of Eureka Flat on the way to Lower Monumental Dam

Concrete haul road on Eureka Flats