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. 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. 

Chasing Erratics on the Great (Kitsap) Peninsula.

Yesterday I decided to go on a little adventure and investigate some of the known glacial erratics that I had heard of on the Great (Kitsap) Peninsula, specifically in the Illahee Area.

A glacial erratic is a piece of rock that differs from the size and type of native rock in the area on which it rests. They are carried by glacial ice, often hundreds of miles. Erratics can be as small as pebbles or larger than a building.

Erratics are common on the Great (Kitsap) Peninsula because this area has been subject to half a dozen or more glaciations over the past 2 million years, with the last one ending 16,000 years ago. During these glaciations, a large tongue of ice known as the Puget Lobe advanced south to fill the Puget Lowland as far as Olympia. Over the Great Peninsula, it was probably well over 2,000 feet thick! More than enough to flow entirely over the top of Green Mountain and the rest of the Blue Hills.

The extent of the Puget Lobe of the Canadian ice sheet. Photo courtesy of Washington DNR. 

Since this glacier came from the north, originating in southern Canada, it was plucking pieces of rocks off the mountains there. The rock types found in the Canadian Rockies and coast ranges are much different than those found here on the Great and Olympic Peninsulas, mostly granites and metamorphic rocks. Our hard bedrock here is either igneous rock of the Blue Hills or sedimentary rock of the Blakeley Formation. So if you see a granitic rock somewhere on the Peninsula, whether it be your yard, a beach, or a park, you can assume it's a glacial erratic.

We likely have hundreds if not thousands of significant glacial erratics on our peninsula. Most of them are probably buried beneath the surface, trapped in the thick glacial formations. This point was illustrated to me quite nicely when I was watching a well being drilled near Central Valley, it encountered a glacial erratic along the way down, and suddenly shards and flakes of beautiful granite came flying out!

However, there are some sizable erratics on the surface that you can find. Yesterday I found 3, which are listed below.

• Ther is a glacial erratic in the Almira Drive parking lot for the Illahee Preserve in East Bremerton. This is a metamorphic rock showing smooth surfaces probably polished by glacial ice as it was transported. 

The Illahee Erratic, with a telephone pole for scale. 

• There is a large glacial erratic on the east side of Illahee road just as the road begins to drop towards the coast traveling northbound. This is one of the largest erratics I have seen on the Peninsula. And interestingly. It is not granitic or metamorphic, it appears to be a large chunk of basalt, which means it may have been plucked from the Olympic Mountains.

• On the corner of Trenton Ave and Fernwood Street, in a lucky person's front yard, is a huge glacial erratic of Blue-Gray volcanic rock suspiciously similar looking to the rocks found in the Blue Hills. Perhaps it was plucked off of Green Mountain or one of the surrounding summits? The best viewing for this erratic is in the pullout on the west side of Trenton Ave, please respect the landowner's property by not attempting to go into their yard. 

These are just a few of the many significant erratics that are scattered around the peninsula, as I stumble across more, if they are substantial enough, I will do a write up for them too. I know there are several in North Kitsap, so perhaps I'll go explore up there sometime in the near future. Summer is just around the corner, and geologic adventures are everywhere in Washington State and the Great Peninsula!

Geomorphology of the northern Thorp Region

The small hamlet of Thorp, Washington, lies about 14 minutes to the west of Ellensburg as the cwu geology van drives. It is located in the Yakima River Valley, the namesake of which meanders it's way north of Thorp slowly making it's way southeast. 

Today I ventured out on a field trip with my Geomorphology class to observe some of the Geomorphological features of the area. What is Geomorphology? Just break it up! Geo=Earth, Morph=Change, and Ology=To Study. So putting it all together, it's the study of landforms created through geologic processes. 

The first feature we observed was the most interesting to me personally. Almost 2.8 miles due north and a little west of Exit 101 on Interstate-90, is a large hillside comprising of ancient Yakima River Sediments. At this point, 1.5 to 5 thousand years ago, the hillside failed. Possibly driven by weak clays or saturated soils, a massive rotational-slump type landslide broke loose. The resulting earth flow at the foot of the slide shoved the Yakima River south by several hundred feet. 

Looking across the large landslide north of Thorp. Photo by Micah K. 

From an overlook at the western edge of the landslide, my Geomorphology class looked across this landslide. The displaced material had taken on a hummocky appearance, with the blocks tilted slightly towards the failure headwall. The size of this thing was boggling, even while small in comparison with the landslide that, for example, decapitated Mount Saint Helens in 1980 with catastrophic results. Even the several houses that were built on top of the landslide deposits seemed small in comparison. It was truly amazing.

Northwest of Thorp, Interstate 90, climbs up another large slope and across the wide, rolling expanse of basalt boulders and sagebrush known as the Thorp Prairie. It's strangely empty up on this expanse, only being occupied by several old and dilapidated windmills, and crisscrossed by irrigation canals. The reason for this emptiness being most in part for it's geology. Thorp Prarie sits on a massive terminal moraine formed many thousands of years ago when a large glacier flowed down the Yakima River Valley. The heart of this moraine is filled with rocky glacial garbage, scraped out from the mountains and dumped here as the glacier retreated, too rocky to farm on, and not very suitable for irrigation, this, it has remained relatively untouched. 

As the Yakima River carves it's way through this moraine to the north, over thousands of years it has created several large flood terraces visible on the flank of the moraine and elsewhere in the valley walls. These large flat expanses are sometimes built directly on top of Columbia River Basalt, which is exposed in the deepest parts of the canyon by the river. And as luck would have it, I'm going to see a important portion of the Columbia River Basalt tomorrow. So...to be continued......

Erosional Remnant of the Columbia River Basalt. Photo by Micah K.