Multiple Deformation Darrington Formation

I had a venture into the Northwest Cascades that included a chance to check a couple of old quarries. The quarries were readily apparent in lidar bare earth imagery, but a bit obscured on the ground as the forest had grown up around them. The first quarry mine floor was being pioneered by a mix of cottonwood and red alder trees. 

The geology of this area east of the South Fork Nooksack River is mapped as Darrington Phyllite and glacial drift and the quarries were in both formations with the one pictured above being in the Darrington Phyllite. The quarry exposed the highly deformed phyllite that includes a range of tight folds, kink bands and mini slip zones.

The Darrington Phyllite covers an extensive area of the Northwest Cascades with outcrops from as far east as near Marblemount to the west end of Samish Island. The same multiple deformation fabrics I observed at the quarry are also present miles away at excellent exposures on Samish Island. Dunhan (2010) working from excellent exposures on Samish Island did a detailed analysis of the deformation including how the kink bands so prominent in the formation developed.  

The Darrington is part of a larger terrain, the Easton Metamorphic Suite, a tectonic terrain of ocean crust that accreted to North America about 140 million years ago. The Darrington is mostly former mudstone that has been metamorphosed into phyllite. The multiple deformations in the Darrington represent different tectonic events in the history of the Easton Suite. Metamorphic minerals within the former ocean floor basalt record one time very deep burial of these rocks indicating the Easton Suite went deep down the subduction trench. Further deformation would have taken place when these rocks were exhumed or uplifted out the deep burial in the trench and then deformed yet again when subsequent tectonic events emplaced them in their current position with additional deformation during the most recent mountain building events. A hard story that has taken time to piece together by lots of geologists with still much to resolve and interpret.    

Just to the east of the quarry the geology changes abruptly into an entirely different tectonic terrain, or more appropriately multiple tectonic terrains termed the Bell Pass Mélange. In the midst of the mélange of terrains is a large block of dunite derived from the mantle of the planet. This block of mantle forms the jagged peaks of the Twin Sisters Range. The Twin Sisters were in and out of the clouds during my venture.

Twin Sisters Range

Blowing Dust in Skagit and Douglas Counties

Last week while on the Waterville Plateau in central Washington I observed a bit of a dust storm to the east in the early morning.

   

Blowing dust on the north side of the Waterville Plateau

Distant haze suggest dust blowing further east 

The dust blow was from an area that burned last September that is also underlain by glacial lake sediments. Glacial ice from the Okanogan ice lobe blocked the Columbia River forming a large ice margin lake. The lake sediments are very fine grained and readily will erode via both water and wind from areas of disturbed ground. 

More surprising was the dust storm mid day today on the Skagit River delta.

April and May have been dry on the Skagit delta/flats and the fields are drier than usual. This is generally a good thing as wet springs can hamper getting out on these fields -- they are just above or at sea level (think Netherlands and dikes that keep the tide out). Most of the dust was from potato fields that were recently plowed. They get plowed pretty deep and pretty late with some not yet planted. However, one corn field just sprouting was kicking up dust as well. The pictures are from between Edison and Allen, northwest of Burlington.

Dust lifting off plowed field obscuring the view of Blanchard Mountain

Dust lifting off field with Bayview Hill in the distance

Driving across the Samish Flats was an eastern Washington experience

The dust blow lasted a few hours but ended as the wind calmed a bit and spring shower passed through. 

I sent a few pictures to Cliff Mass and he has a write up on today's wind event: dust-storms-on-both-sides-of-cascades. Cliff included some pictures from the Tri-City area, a place where I experienced my share of dust storms. 

Josh Ritter starts a song that is apt for dust storms and farming: "Dirt roads and dryland farming might be the death of me. But I can't leave this world behind" Josh Ritter - Lawrence, Kansas. I will just note that all the rain in Skagit winters precludes dirt roads in the farm land.

Late Low Snow and Rosie Has a New Baby

On Monday I headed to central Washington via the Highway 20 across the North Cascades over Rainy Pass and Washington Pass. A cold rain was falling in the late afternoon as I crossed the passes. The sky cleared by the time I reached the Columbia River at Pateros so I opted for camping at a favorite site that will remain secret. When I got into my sleeping bag it was 63 F -- a bit warm for sleeping, but by morning it was 36 as the cold air caught up to me. 

It was hard to tell as the mountains still have lingering late snow, but it looked like there was fresh snow on the North Cascades in the morning. 

I had to head back Tuesday and noted the fresh snow on the trees and peaks on my return. 

Liberty Bell approaching Washington Pass

View of Fisco Mountain while descending from Washington Pass 

View of high ridge between Colonial Peak and Pyramid Peak on the descent to the Skagit River

 Late Wednesday even Lyman Hill at 4,000 feet in the Northwest Cascades had a dusting of snow on its upper slopes added to the older snow on the clear cuts.

Our neighbor Rosie delivered as least one fawn on Wednesday. Three years ago Rosie somehow got her nose torn up; hence my name for her. She typically has previously had twins so another may be on the way. Our other neighbor, Blackie, has not made an appearance yet, but I expect she will be around with her fawn or fawns soon.

 

Geoducks

I have spent a fair bit of time on the high bluffs along the east side of Port Discovery. During some of those ventures a small boat has been off shore in a stationary position with the sound of engines running. At other times the boat is simply anchored near the end of an unpaved road adjacent to a cuspate shore form.  

Landslide complex with cuspate shore form in distance and anchored boat

Port Discovery with Olympic Range in the distance

The boat is used by divers for harvesting a lease tract subtidal geoducks. Dave Williams has an excellent write up of the history and management of the resource (pugetsound.org/geoduck-clams). The shellfish can be harvested during very low tides without diving.  (b-roll:-geoduck-beach-harvesting-aquaculture). However, a fair bit of the harvest is via dive boats at lease sites (youtube.com Geoduck Diving Harvest). The geoduck fishery is managed by Washington State Fish and Wildlife as well as the owner of the subtidal lands, Washington State (dnr.wa.gov/wild-geoduck-fishery)

The first time I tried geoduck was via a gift from shellfish business I did some geology work for. I have since dug for them a few times during very low tides. They are a fun prize to pull up out of the sand. One big goeduck is more than enough for a meal. But those big geoducks take many years to grow. As their value has increased management of the resource has become more important.    

From the Columbia River to The Fraser River in 1824 - John Work

I roughed in the route of a 1824 Hudson Bay Company expedition from Fort George, the former Fort Astoria trading post, to what was later to become Fort Langley via Journal of John Work, November and December, 1824 via T.C. Elliot, 1912. 

Part of the scheme was to find the location of a trading center fort on the Fraser River that could receive export goods (furs) from the interior of western North American. Hudson Bay Company (HBC) was already concerned that the lower Columbia would end up in American possession. In part because Fort George was originally an American establishment. In addition, at that time navigation from the sea to the lower Fraser was far superior to the harrowing crossing of the entrance to the Columbia. However, while the Fraser River was a better sea access point, the Fraser River was not a good river transit route.  While a fort ultimately was built, Fort Langley, the Fraser proved to be an impossible navigation route from the interior.

The journal is a window to a different time, and for that matter a different place. I have been fascinated by the diversity of the people and interactions that took place in the brief period from 1790 to 1825. The assembled team for the venture clearly had a pretty good idea of the route they should take. The team included several Hawaiians (Islanders) as well as an Iroquois hunter and his slave.   

Note the time of year they traveled, November-December. While it does rain in November and December in western Washington, the outer coast and the southwest part of the state gets 'heavy rain', a term that Mr. Work used in his journal of his venture (correct spelling of his name was Wark). This was a hardy group. I contemplate how I would have performed portaging across wet ground and along shorelines, rowing for many miles, and camping in the rain, the heavy rain.   

Rosario Fault on Crane Island north shore

During a work venture in the San Juan Islands I got a nice look at the bedrock along the north shore of Crane Island. Crane is a rocky island between the southwest end of Orcas Island and the northwest shore of Shaw Island. The ferry between Orcas and Friday Harbor passes along the south shore of Crane, but on this venture I was in a small boat and we ventured along the north shore. 

Crane Island is mapped as Constitution Formation on both the Bellingham 1:100,000 map (Lapen (2000) and the Roche Harbor 1:100,000 map (Logan, 2003). And both maps denote the Rosario Thrust Fault immediately to the north of Crane Island 

Portion of Bellingham Quad geology map (Lapen, 2000)

KJmc = Constitution Formation, JTRmcto = Orcas Chert, pPscg = Garrison Schist, pDit = Turtleback Complex, Qgd = glacial drift. Heavy black lines with saw teeth are thrust faults with teeth on upper plate.

Portion of Roche Harbor Quad geology map (Logan, 2003)

The Rosario Thrust is where the Constitution Formation has been faulted up over the Orcas Chert. The fault zone is a zone of highly sheared rock that in places include slivers and slices of other formations caught up in the fault zone such as the Garrison Formation denoted by Lapen (2000) on Shaw Island south of Crane Island. 

My observations of the fault zone exposed along the base of the steep north slope shoreline on the north side of Crane were consistent with other areas where the Rosario Trust Fault is well exposed along the shore near Rosario on Orcas Island (hence the faults name) and along the southwest shore of San Juan Island. The shoreline areas typically offer the best exposures of the fault zone.     

Highly sheared rock within the Rosario Thrust along the north shore of Crane Island

Brecciated and sheared bedrock at water line

Massive block of Constitution Formation above shear zone

On the uplands of Crane Island, the bedrock is generally massive metamorphosed sandstone of the Constitution Formation.  

Typical massive silica-rich metamorphosed sandstone

Orcas Chert is primarily composed of ribbon chert, alternating layers of silica rich 1 to 2 inches thick with thin layers of shale. The chert is derived from the accumulation of silica diatoms that accumulated on the ocean floor. The shale was derived from fine dust and silt that also reached the ocean floor. The layering developed after deposition when the ooze of silica rich and silty sediment was compacted. The age of the Orcas Chert is between 180 and 280 million years old. The Orcas Chert is part of terrain consisting of the related Deadman Bay Volcanics, which are ocean floor pillow basalts that are somewhat older than the Orcas Chert and likely formed the basement that the silica rich sediment that formed the chert unit was deposited on. The original depositional setting was an ocean floor area far from North America. The formation was moved to and accreted to the edge of North America via plate tectonics. During accretion the Orcas Chert was metamorphosed at high pressures.

The Constitution Formation was also originally an ocean floor assemblage; however, this unit is on the order of 130 million years old. The Constitution Formation consists predominantly of metamorphosed fine sandstone derived from a volcanic arc. There is some chert and basalt in the unit as well. This formation was also accreted to the edge of North America. A lack of older aged sediment, North America sediment, suggests the sediment may have been derived from an ocean island arc. 

The Rosario Thrust Fault and the juxtaposition of the Orcas Chert and Constitution Formation took place after accretion -- note that the younger Constitution is thrust over the older Orcas Chert.    

The map pattern shows that Crane Island is klippen of Constitution Formation on the underlying Orcas Chert. Parts of the Constitution Formation have been stripped away leaving the Constitution Formation as an 'island' on the Orcas Chert and as well as the rock formation that makes up most of Crane Island. 

 

Political Sunday: Remembering Malden and Pine City Okanogan Valley

Malden Post Office before the fire

NPR did a brief story on Malden, Washington and the lack of a National Major Disaster Declaration after the wildfires in Washington State in early September (HERE). The wildfires in early September burned nearly all of the town including the town hall, post office, food bank, library and fire station. Pine City, a few miles away also was badly burned and one fire burned across 60 miles of Okanogan County and into Douglas County including burning into the City of Bridgeport. 

The NPR story provided no explanation as to why a National Major Disaster Declaration has not been issued. One theory is politics because Washington State votes Democrat of late and the President does not care for the governor; however, Malden is located within a US Congressional District represented by Cathy McMorris-Rodgers, a Republican. The Okanogan area is represented by another Republican, Dan Newhouse. Malden voted 2 to 1 for Donald Trump for President over Joe Biden. So if the reason is politics, it is doubly unfair. Ms. McMorris-Rodgers stated shortly after the fire "I will be working with and supporting state and local officials and doing everything I can on the federal level to ensure our communities have the resources they need to rebuild." She, did sign along with the entire Washington US congressional delegation a letter to Mr. Trump in support of Declaring a Major Disaster (murray.senate.gov/letter).

So far Malden does not have the resources to rebuild. The town had an early burst of development when the railroad came to this location with a rail stop in 1906. After the railroad pulled out their facilities in the 1920s, the town declined. There is no commercial activity remaining, but with over 80 homes destroyed, Malden will have a hard time bringing their community back without help.