Showing posts with label Creek. Show all posts
Showing posts with label Creek. Show all posts

Thursday, June 4, 2020

A New Perspective: The Ecologic and Geologic Oasis of Stephenson Canyon, Bremerton.

A sudden wave of nostalgia washed over me as I followed my friend and Kitsap Sun reporter Josh Farley into the depths of Stephenson Canyon. I had last stepped foot here over five years ago, at the very start of the "Kitsap Waterfall Survey" project. 

The canyon was filled with various shades of greens and browns, exploding with the growth of mid-spring. Carpets of sword ferns filled the understory, with large Big-Leaf Maples, Western Red Cedars, and Douglas Firs creating the canopy a hundred feet above our heads. And of course, down at the bottom, Stephenson Creek chattered away, beckoning. 

A "pocket wilderness" inside Bremerton city limits. 

I've learned so much since I first stepped into the canyon. In 2015 I couldn't have cared less what kind of plants and ecology the canyon hosted; I only cared about rocks. Now, I was taking it all in through a new set of skills and experiences. I looked up and around as well as down, remarking the enigma of such a beautiful Pacific Northwest oasis in the middle of a significant city. Craig Romano described it well in Urban Trails: Kitsap when he called it "...a pocket wilderness that feels like it can be deep in the Olympics." 

Of course, it wasn't entirely without flaw. Invasive English Ivy besieged several trees on the rim and down into the canyon, and trash and old city refuse was abundant. A community cleanup effort here would probably breathe some new life into the area, and the city would do well to pay more attention and protect this beautiful piece of borderline old-growth ecosystem. 

Moving on, we descended into the canyon and crossed the creek, moving our eyes away from the canopy and down to the ground. Various cobbles and boulders lined the stream channel, and the footpath traversed some small but textbook stream terraces that probably get a new layer of sand and mud every time the creek floods. 

Our main destination, of course, was "Stephenson Canyon Falls." The little cascade I "discovered" so many years ago. We rounded the corner, and the first words that flashed into my head were, "I'm an idiot." 

Back in 2015, I had no geology education other than a couple basic geology classes, and I hadn't done a whole lot of research on the geology of the bedrock underlying the Kitsap Peninsula. The extent of my knowledge was that most of the bedrock in the area was basalt. So I had assumed that the falls dropped over basalt. I was dead wrong. 

"Stephenson Canyon Falls" with slightly dipping beds of the Blakeley Formation
"Stephenson Canyon Falls" with slightly dipping beds of the Blakeley Formation. The Falls drop over possible sandstone, while the satchel sits on mudstone/siltstone.

"Stephenson Canyon Falls" actually drops over a resistant ledge of the "Blakeley Formation," a much younger rock with a completely different origin than the basaltic rock that makes up the Blue Hills. The area around the falls exposes two types of rock within the Blakeley Formation. The base of the falls is made up of siltstone or mudstone, and the falls themselves drop over what might be a sandstone with larger softball-sized class embedded within it. I have my own interpretations of what this layer might be, but I'm going to hold off on that until a later date after I do more research. 

Downstream of the falls, Stephenson Creek flows over and alongside some of the nicest Glacial Till deposits that I've seen on the Peninsula. Blue Gray concrete-like deposits form shelves and small embankments, peppered with glacial erratics and small potholes drilled during times of flooding or high water.


An exposure of glacial till with a carved pothole at the bottom of Stephenson Canyon. 

After viewing the falls and surrounding geology, it was time for Josh to head back. We made our way downstream again, where we stumbled upon an absolutely titanic Douglas Fir Tree, possibly an old-growth giant from before the first caucasian colonists arrived in Western Washington. It was a sight to behold and was a great symbol that despite the surrounding urban sprawl, Stephenson Canyon is still very much wild. 

Monday, February 5, 2018

Kitsap Waterfall Survey: "Lower Lost Creek Cascades"

Well over a year since I've last surveyed a waterfall on the Kitsap Peninsula, this was a nice return to form. Several months ago, a friend of mine mentioned to me the existence of a small cascading type waterfall on Lost Creek within publicly accessible land. With me being busy at CWU, it was put on the back burner at the time. Not anymore, This past weekend (2/4/2018) I joined my friend, his son, and their dog and set out to document and photograph this cascade with my own eyes.

Our waterfalling dog companion, Delilah.
A half-mile after it's opening fanfare, Lost Creek encounters another outcrop of Siletzia bedrock which underlies much of the Kitsap Peninsula. The canyon walls and creek bed become lined with a gorgeous blue-green-gray basaltic rock. After tripping over a small rapid in the shadow of a massive fir stump, the creek flows around a bend and slides over a ten-foot drop into a beautifully secluded alcove with a surprisingly deep plunge pool.

The initial 10-foot drop of "Lower Lost Creek Cascades" 
Immediately after this drop, the creek narrows from 10 feet wide to less than 3 feet and careens through a narrow slot cut into the rock, dropping an additional 4 feet in the process. The force of the water tearing through this slot has drilled large circular potholes into the bedrock, making interesting shapes and formations.

Lost Creek tearing through the small defile, with several large potholes in the foreground
Immediately after the main slot, the creek funnels through another bottleneck in the rock in a slide 3 feet high slamming into a jutting rock, taking a 90-degree turn to the left and bouncing over a couple small drops, before leaping over a messy 5-foot rock face. This final drop ends in a rocky alcove similar to the large one upstream. Shortly downstream, "Lower Lost Creek Cascades" terminates in a final small 3-foot slide, bringing the total height to ~25 feet.

The bedrock lining the creekbed. 
The geology of the canyon here is both fascinating and stunning. The underlying grey-blue gabbro rock sets the tone, peppered with red-brown pieces of basalt, and cut with white veins of quartz and calcite. In quieter pools and gravel bars, occasional light colored granite clasts can be found from the overlying glacial debris mantling the entire peninsula. At least at one spot within the cascade, I found evidence for faulting and the intrusion of volcanic andesite dikes 50 million years ago. I plan to write posts on both those geologic stories in the near future.