Chuckanut Drive, a.k.a. Washington State Route 11, is one of the premier attractions here on the extreme northwestern fringe of the U.S. “The Nut”, as I like to call it, winds for just over 21 miles between Bellingham and Burlington. Hemmed in by the Chuckanut Mountains to the east and numerous scenic bays, inlets, and islands on the west, it offers a stunning variety of scenery for such a short stretch of road. Chuckanut Drive has truly been a gift to me the last year and a half, because I can be cruising down it (well, as least what passes for “cruising” in a 16 year old Corolla…) and taking photos within 5 minutes of leaving my house. I’ve done this several times recently, now that the Sun is once again gracing us with its presence past 4pm.
Chuckanut Drive is chock full of destinations that make you feel further from civilization than you actually are, places that are perfect for occasions when time is in short supply. One of my favorite such spots is the beach walk at Chuckanut Bay. Fortunately for me, it also happens to be one of the closest, sitting just barely inside Bellingham city limits. Close enough for me to walk if I was feeling ambitious. Nearly inaccessible at high tide, once the water level drops a couple of feet, a few hundred yard stroll to the northwest shore of the bay puts you in the middle of spectacular and bizarre rock formations sculpted out of the Chuckanut Sandstone by freezing sea spray that accumulates along the margin of this sheltered cove. This is also a great place to see honeycomb weathering features along the shore, as is adjacent Teddy Bear Cove.
Chuckanut Drive is heaven for the geologically inclined for a couple of reasons. For one, the road itself is built on layers of weak sandstone that slope precariously towards the sea. When it rains, water seeps into the spaces between the layers, dramatically decreasing something called the coefficient of static friction, which is normally responsible for keeping the rock intact. In other words, the water essentially lubricates the surface between rock layers, causing causing large chunks of the hillside to frequently slough off, making Chuckanut Drive one of the most landslide prone highways in the state. Last winter, it seemed like the road was closed at least every few weeks in order to repair large gashes in the pavement caused by falling boulders.
Two, the sandstone exposed here, a rock unit known as the Chuckanut Formation, is chock full of fossilized ferns, palm fronds, gingko leaves, wood, and bark, relics from a time when the Pacific Northwest was just as wet as today, but a whole lot warmer. An exposure of this same rock unit an hour to the east even turned up a footprint of a giant Eocene flightless bird a few years back, which is now on display at Western Washington University.
A few miles further south of Chuckanut Bay is Larrabee State Park, the first state park in Washington, whose landscapes and marine life I’ve documented previously and continues to be a favorite spot to catch the sunset:
Heading south from Larrabee State Park, the road becomes increasingly curvy and narrow as it clings to the hillside passing oyster bars, cascading waterfalls, and smattering of million-dollar homes. (You never actually drive along the coast proper, that route is reserved for the Burlington Northern Railroad, but the views are even better as a result.) Keep your eyes on the road and wait for one of the plethora of pull-offs where you can take it all in without running the risk of driving off a cliff.
A short but steep hike from near the route’s southern end puts one at Samish Overlook, which offers unparalleled views of the San Juan Islands, the Skagit River Valley, Olympic Mountains, and even Mt. Rainier on a clear day. On days when the winds are right, this is a launching point for local paragliders. It’s also a cool place to go during a foggy spell; at nearly 1300 feet above sea level, the Overlook sits above the fog deck most days making for spectacular sunsets and less than spectacular dark and foggy hikes back to your car.
The last nine miles of the route angle away from the mountains and coast and traverse the flat lands and fields of the Skagit River Valley. But just a few miles west of the Drive, along Bayview-Edison Road, you’ll find the Padilla Bay National Estuarine Reserve, which operates an excellent interpretive center with exhibits about the coastal ecosystems of the Puget Sound area and a small aquarium. This is also a great place to spot a number of the bald eagles that visit the Skagit River Valley and surrounding area each winter to feast upon dying salmon. Padilla Bay (actually an estuary) is so shallow that at low tide, mudflats extend for hundreds of yards away from the coast.
Eventually, Chuckanut Drive meets up with I-5 in Burlington, just a few miles north of the infamous I-5 bridge that collapsed into the Skagit River last year. From here it’s a quick 15-20 minutes drive back to Bellingham along the interstate. Or if you feel like braving that bridge, I hear there are a few good breweries in Mt. Vernon….
My college English professor once told me that a great way to hook people on a story is to begin with a personal anecdote. Though now that I think about it, he also told me that bacon was bad for me and that my writing was good, so I suppose I should take anything that came out of his mouth with a grain of sodium chloride. But heck, I’m even prefacing the primary anecdote with this secondary anecdote so you should probably just read anyways.
Let me set the scene for you: Bellingham, Washington; nestled along the coast where the Strait of Georgia and the Strait of Juan De Fuca merge together to form a bewildering assortment of coves, islands, bays, and inlets, where half the license plates you see on the highway are from British Columbia, in the only place where the occasionally explosive Cascade Range makes its way allllllll the way down to the beach, and where the nearly 11,000 foot ice sculpted summit of Mt. Baker dominates the view from town on 100% of the 25% of the days out of the year when there is actually a view from town. (Read that again if you need to…) You see, Bellingham is really cloudy. It also happens to be where I currently reside. I’m not trying to knock Bellingham; it’s a great town in a myriad of different ways. Really great. The pictures on this page should prove that. But it’s really, really, REALLY cloudy. Especially in the winter. When I first got here I had a professor tell me that a sunny day is a perfectly legitimate excuse for turning in an assignment late. Many days I wake up, open the blinds, and think that I must be watching an old episode of Gilligan’s Island…you know, the one’s before they started making it in color? In fact, the official motto of Bellingham is “The City of Subdued Excitement”. I am convinced that this is mainly because it’s a little hard to be anything other than subdued when a gray pall can settle over the city for weeks on end. It’s like nature’s Vallium.
Anyways, the anecdote. Upon the advice of professors, students, and other acquaintances familiar with the winter…er…”conditions”…here, way back in September (one of only three months out of the year where it is statistically more likely to be partly cloudy or sunny than completely overcast) I made a visit to Rite-Aid with the intent of purchasing some Vitamin D tablets. Now let me assure you that the vitamin section at Rite-Aid is the very epitome of robust; my local store stocks about eight different complete lines of nutritional supplement products. Vitamin A, Vitamin B, Vitamin C, Vitamin Q, calcium, magnesium, iron, glucosamine, corn silk, echinacea, fish oil, cod oil, beet juice, cow bile, pig urine extract…it was all there. Except for the Vitamin D, whose slot on the shelf belonging to each and every brand was completely empty. An omen if I’ve ever seen one.
Now that I have (hopefully) made my point, the question becomes: can we quantify just how cloudy Bellingham is? On the surface, one would think that composing a list of the cloudiest cities in the United States would be a relatively straightforward exercise. You would be wrong. It turns out that a variety of methods exist to generate such a list. One can, for example, calculate the total number of overcast hours per year expressed as a percentage of possible daylight hours (if that made any sense at all). Others prefer instead to count simply the number of days in which the Sun remains hidden behind clouds for the entire day, or the number of days in which the sky is overcast for more than 50% of the daytime hours. And none of this even begins to take into account this potentially thorny issue: what constitutes “cloudy”, exactly? Should “partly cloudy” count as “cloudy” or “sunny” in a tally? One imagines that the answer to this depends on weather the meteorologist undertaking this task is more of a “glass half empty” or “glass half full” kind of person. And what about night? Do we care if it is cloudy at night? Or are we only interested to know how much sunshine we are losing? As an astronomy enthusiast, I demand that the percentage of cloudy nighttime hours be taken into account. As you can see, madness is never that far away.
The lack of any well-established protocols when it comes to defining “cloudiness” leaves ample opportunity for cities who rank highly on one list to try and come up with a new way of calculating the list that moves them down a few spots. Or, ideally, out of the top 10 entirely. After all, you don’t see too many glossy tourist brochures exclaiming “Come visit the 3rd cloudiest city in Washington and enjoy a vacation without the hassle of having to reapply sunscreen every 3 hours!” Catchy as it sounds, it just doesn’t sell. (However, if you happen to be a tourism exec from Aberdeen, WA and you are interested in licensing this slogan for use in your promotional materials, please contact me using the oh-so-appropriately named “Contact” link above!) Regardless of which metric you use though, Bellingham, Washington generally ranks near the top of such lists. If it doesn’t, chances are the makers of the list are interpreting the word “city” rather loosely and including every little hamlet and village on the Olympic Peninsula in their calculations, yet another devious method of getting yourself off the list.
To give you some perspective on my rant, I feel obligated to disclose that I grew up in Flagstaff, Arizona, a city that receives, on average, more than 300 days of sunshine per year. Such a concept is about as foreign to Western Washingtonians as a hurricane warning is to Saskatchewanians. The rain here is different too. During a lecture on precipitation last quarter, one of my professors asked the class, composed almost entirely of western Washingtonians, if anyone had ever experienced a “thunderstorm“. Less than half of the class raised their hands. More often than not, we experience what someone in New Zealand would call “pissing”, a steady, extremely light rain that that lasts for days and yet somehow manages to thoroughly permeate everything with dampness despite never requiring you to change your windshield wiper setting from “intermittent” to “warp speed”. However, when the rain finally ceases and the clouds part, the emotions experienced is roughly on par with the feeling that Arizonans get when it rains for the first time in months. Everyone just sort of stops whatever it is that they are doing (including driving apparently…as much as it rains here, you’d think people would be better at driving in it) and goes wandering around outside looking up at the sky, squinting, and trying to figure out what the hell is happening.
And then there’s me. While everyone else stumbles around in disbelief, I grab my camera, put on my hiking boots, and head to the nearest beach, mountain, waterfall, overlook, or trail to enjoy and photograph a majestic landscape that truly deserves to be uncloaked and put on display far more often than it is. But naturally, I do all of this in an extremely subdued manner.
Continuing on with our recent geological theme here at Pyroclastic Pixels (you’d almost think I was a geology grad student or something…), today we are going to take a look at one of the most picturesque geological curiosities you’ll ever find: honeycomb weathering, also frequently referred to as “tafoni”. Those two terms aren’t really exactly quite completely equivalent but we’re not going to journey down the nit-picky fork in the road today. Honeycomb weathering is pretty cool. About the only thing that would make it better is if the holes were actually filled with honey. That joke sounded way better in my head than it looks on the screen.
Specific geographic and geologic conditions are needed for honeycomb weathering to develop, yet these conditions can be satisfied in a variety of places, from the arid deserts of the American Southwest, to the storm-battered shores of the Pacific Ocean. Here in northwestern Washington State, honeycomb weathering occurs along the coast, along and just above the high tide mark, in areas where a rock unit known as the Chuckanut Formation is present. The pictures on this page were taken at Teddy Bear Cove, just south of Bellingham, WA, which has some of the most spectacular examples I’ve ever seen. The Chuckanut Formation, or “the Nut” as I like to call it when I’m feeling lazy, is a thick series of sandstones, conglomerates, and occasional coal seams that were deposited about 60 million years ago when NW Washington occupied a large basin at the foot of an ancient mountain range that occupied more or less the same space that the Modern Cascades now occupy.
There is a good reason that sandstone is one of the rock types most susceptible to this type of weathering. Sandstone is essentially composed of countless tiny, sand-sized particles of various minerals (mostly quartz and feldspar in the case of “the Nut”) which are held together by some sort of substance, known as cement, that “glues” them all together into a solid mass. In most sandstones, this substance is either calcium carbonate (CaCO3) or silica dioxide (SiO2), also known as quartz. Honeycomb weathering forms when salt-laden sea spray lands on the sandstone. As the salty sea water evaporates, tiny salt crystals form on the surface of the rock. The growth of these salt crystals on the surface of the rock physically separates the sand particles from the cement. Over time (a long time…), this creates a small depression in the rock. Once a small indentation forms, a positive feedback effect is created; the hole has a greater surface area than a flat surface and thus more rock is exposed to incoming sea spray. Sand grains are thus separated from the cement at a faster rate, thereby enlarging the hole. In some locations, you can actually see little piles of sand grains in the cavities, grains that were once part of the rock but have now been forcibly removed by the salt. I’ve found that this is most prevalent in areas just above the high tide line where wave action can’t wash the sand grains back out to sea.
But Zach, you say…how then does honeycomb weathering form in places like the desert Southwest where the closest thing to sea spray you’re going to find is mule deer pee? Ah…well I’m glad you asked. We often observe honeycomb weathering in sandstone in places such as Southern Utah that are far away from the sea. I had some difficulty finding a halfway decent picture of desert honeycomb weathering from my archives, but I was able to find one that I took in 2008 in Capitol Reef National Park (see below). If you want to see a lot better examples, just do a Google image search for “Utah tafoni”. While the exact cause may vary, and the individual pits tend to be larger, the process involved is essentially the same. We still need to find some way to separate our sand grains from the cement. Many washes in the southwest are dry for most of the year but are very rich in dissolved salts when they do flood. In desert environments, it’s no surprise then that we tend to find honeycomb weathering predominantly along dry stream beds and canyons. When a flood comes through, even though the water may not be as saline as the ocean, it is still salty enough to form small salt crystals when it evaporates, which it invariably does. In other locations, slightly acidic groundwater percolating through rocks can actually chemically dissolve calcium carbonate cement, leaving the sand grains with nothing to cling to.
Hard as it might be for you to believe, this has been only a cursory explanation of the honeycomb weathering formation process. If your brain hasn’t begun to resemble honeycomb weathering by now and you are interested in the gritty details (perhaps you arrived here in the process of researching a paper or maybe you’re a geology nerd like me and just like knowing about such things), an excellent academic paper on the formation of honeycomb weathering can be found here. Regardless, your next step should be to pull out a geologic map, find the closest beach with some sandstone, pull your boots on and go find yourself some honeycomb weathering! Or you could always just look at the rest of these pictures I suppose…