Friday, March 31, 2017

Waterfall on Vedder Ridge and the Sumas Valley

I previously posted on Vedder Wall noting its glacial origin. There is a seasonal waterfall on steep cliff face that was visible during a recent trip to the Sumas Valley.

Based on the elevation of the top of the wall at this location and the valley floor, I estimate the falls to be about 400 feet.

Prior to checking out the waterfall view, I had had a very wet day. I was fairly pickled by the rain as well as the need to do a bit of stream wading. So it was nice to have a bit of late afternoon spring sun, and despite the wet weather spring has arrived in the Sumas Valley below Vedder Mountain.

Spring hay and the view across the Sumas Valley floor to the northeast to the Chiilwack and Fraser Valleys

Blueberry field just south of the border

The richness of the Sumas Valley farmland is the result of the area being a former lake that occupied the low area left by the Sumas ice lobe. Keeping the area drained on the Canadian side requires a lot ditches, a pumping station and a levee to hold back the Chilliwack River. With the wet weather and low gradients of the ditches there was still a fair bit of water on the valley floor when I had a view from above the Vedder wall.

Thursday, March 30, 2017

Working Through Theories at an Accretion Shoreform

I had a recent venture to Marrowstone Island in Jefferson County. Just south of the beach access at Fort Flagler ( I noted a well built up shore with driftwood and vegetation on the backside of the driftwood/beach berm. This section of shore is termed by the shoreline wonks as an accretion shore form, that is it shows evidence of beach build up with the accumulation of sediment - in short the beach at this location shows evidence of growth. Enough so that vegetation has become well established on the upper beach. I am not a big fan of the term "accretion shore" because it implies a process stability that may not be very stable. That is accretion can be a temporary phenomena.

I also noted that the trees on the backside of the berm between the berm and the base of the shoreline bluff were mostly dead. Why?

I ventured into the thicket of dead trees with the theory that perhaps the soil had become saturated as the berm had grown and blocked water flow from the slope above and thus killing the trees. However, that theory was killed off when I found no wet ground. In fact the ground was dry despite all the recent rain and the area of the dead trees was covered with thickets of salal, a plant that prefers dry conditions. 

The accretion shore feature continued to the north. Its presence jutting out from the base of the bluff seemed a bit out of place, but along shore spits like this are not uncommon. 

There was a hint as to what might have been the cause of the accretion shoreform near the shore access at the Fort Flagler State Park. Old pilings in the beach suggested a former structure which would have blocked sediment transport or driftwood causing the shore up drift to build out.
Old pilings for a former pier

 The history of the shore was well presented at the shoreline trail access in the park. I was walking this shore reach from a different direction so my seeing the sign was after walking the shore.

Note the large build up of driftwood south of the pier in this photograph

1951 aerial (USGS)

So the likely origin of the accretion shoreform was the past presence of the pier. The wood pilings would block driftwood on the south side but allowed sand to pass through as the south wind generated waves moved sediment generally from south to north.  The pier though not used since the 1950s was still present up through 2006.

Oblique aerial view (Ecology, 2006)

My theory on the dead trees was that the accretion shore form is beginning to erode now that the pier has been removed and thus the trees were being inundated with saltwater on a more frequent basis and the beach had narrowed. Nice theory; however, a closer look at the 2006 oblique aerial shows that the trees were already dead before the pier was removed.

Dead trees can be seen all along the base of the bluff (Ecology, 2006)

A view of the 2002 oblique shore aerial shows that the trees alive in 2002.

Same location in 2002 with live trees (Ecology, 2002)

My theories up to this point have not done well! So a new theory is proposed. A large storm surge in 2006 may have been responsible.

This particular storm along the east shore of Marrowstone Island caused significant shoreline erosion that stripped away the toe of the slopes at many locations along the east shore of the island. That erosion set up ongoing bluff failures that took place in the years that followed once the toe of the slope had been eroded. So my theory is that surge of salt water over the berm may have killed the stand of Douglas firs growing between the berm and the toe of the slope.    

Tuesday, March 28, 2017

Samish Island Heron Rookery Take Flight

Lisa captured a short clip of dozens of heron circling over the Samish Island heron rookery. The great blue herons nest in trees in the forest as a big group. Bald eagles do prey on heron and an eagle caused the heron to take flight in mass.

The heron began the early stages of breeding and nesting within the past few days. 

Thursday, March 23, 2017

This Year's First Skunk

Just about the time daffodils are providing early color to landscaped yards skunk cabbage brings bright green and yellow to wet areas in the forest of western Washington. 

I do not do wetland work, but I do see a lot of skunk cabbage on wet unstable slopes or while traversing through the forest.

Saturday, March 18, 2017

Non Washington: Cap Stones, Surface Exposure, and Petrified Wood

I try to keep the geologic formations straight when venturing on the Colorado Plateau, but the smaller stuff is just as fascinating. Geology nuances that were not as noticed as much as on previous visits. I would note that my non geologists travelling companions generally could care less about the names of formations, but often appreciate an explanation of why things look the way they do.  

One feature is the concept of a hard resistant rock formation forming steep spectacular cliffs with softer rock below protected by the cap rock. 

The cap rocks are the very upper part of the mesa which are underlain by Shinarump Conglomerate of the Chinle Formation. The huge red cliffs are the De Chelly Sandstone of the Cutler Group. Below the sandstone is the softer Organ Rock Shale also of the Cutler Group. 

The cap rock of Shinarump is not very thick at these mesas near Monument Valley, but is the critical protective layer. While the De Chelly Sandstone forms the scenic cliffs and is clearly capable of standing as steep vertical cliffs for very long periods, once the cliff face peals away and tumbles down the slope, the increased surface exposure makes quick work of the sandstone. Hence, there is very little talus apron of De Dhelly Sandstone at the base of these high cliffs.     

Note the lack of talus below the cliff wall where sandstone blocks had previously fallen out of the cliff face. More recent rock falls to the left and right  have not yet been turned into sand. 

If not for the ready breakdown of the De Chelly Sandstone blocks from angular boulders to sand, the monuments of Monument Valley would not exist but instead would be mounds of talus with a low cliff near the top at most. 

Note the near lack of talus blocks at the base of this monument.

The lack of talus also allows for ready viewing of the underlying Organ Rock Shale.

While the hard De Chelly Sandstone is readily turned to sand when surface area is increased post rock fall from the cliffs, some rock types are very resistant to erosion even with large surface exposure. The silica rich petrified forest logs in Petrified Forest National Park weather out of the soft mudstone of the Petrified Forest Member of the Chinle Formation, and in places form a resistant veneer of silica rich wood on the surface or as scattered logs laying on the ground surface after the surrounding mudstone as been completely eroded away.

Note log encased in mudstone on cliff face
Most of the red boulders below the cliffs are blocks and logs of petrified wood. 


Friday, March 17, 2017

Juniper Management in the Mountain Home Range, Utah

Some hard deadlines, too much field time, disconnected from the internet and a vacation has limited posting much on the Washington landscapes. Travel and work out of state though is an opportunity to gain new perspectives.

Earlier this winter I noted that junipers are not a common tree in Washington State (juniper-dunes-wilderness), but elsewhere in the western United States junipers are taking over large tracts of the land.

I noted an odd shape shaped forest feature while flying over the Mountain Home Range in Utah.

The view of this one square mile section is of Utah State owned land. Utah did some juniper clearing on the land to improve grazing but leaving some trees in a shape that stood out when viewed from above. The clearing was done about three years ago. The surrounding land is managed by the BLM with another Utah section just over the ridge. It appears that Utah is being a bit more aggressive on Juniper management, but some of the BLM land has also been treated.

Wednesday, March 8, 2017

Washington Landscape Paintings

Dusk at Padilla Bay, Lisa McShane - oil on canvas

A personal note. A year and a half  ago Lisa and I bought a property on Samish Island that had a shop building that was readily converted into an art studio. Lisa had out grown the tiny studio in the back of our home in Bellingham. She can now work on multiple large canvasses as well as smaller ones.

Some of her recent work is currently on display at Smith and Vallee Gallery in Edison, Washington. The paintings are of places in Washington State that we live near or frequent in our travels. A visit to Smith and Vallee will give you a good flavor of Washington landscape paintings.

Road to Jump of Joe

Chopaka and Palmer between lightning strikes

Cloud over Blue Mountains

Rain shadow Samish Island Road

Moon over Skagit

Guardian Trees