Wyoming 2014 – Day 109 – Cody – Thermopolis: Uplifted

Friday September 5, 2014, 87 miles (140 km) – Total so far: 4,843 miles (7,794 km)

The sun filters through thin clouds to light the landscape with gentle rays. The muted brilliance matches the muted colours of the landscape. There are no bright shades of green or glossy leaves standing turgid with moisture. There is no showy excess of life like we saw in Illinois and Iowa in spring. The sagebrush is…well… sage-coloured and the sparse grasses cured long ago. Here, the rocks and soils are all Cretaceous-aged. Nothing about Cretaceous-aged rock is flashy – they’re almost all shales and sandstones with colour pallets of various browns and grey. This landscape is a lot more about texture than colour. The sandstones form resistant ridges that give the landscape hard angles and definite shapes. The shales are soft and crumbly and give the landscape lumps and rounded edges. Looking far ahead, the land surface on top of those soft shales looks like it was painted with a stubble brush instead of the graceful, fine-lined strokes of a more delicate tool.

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On the road from Cody to Meeteetse. Thank you for the shoulders, Wyoming. Montana, you still suck.

I like the subtle colours because they stand in such great contrast to the harshness of the landscape in general. It is one of the things I love about Wyoming and its basins. There is no question when you leave a town on the edge of a basin that you are about to cross an area that is going to be dry and somewhat desolate. There is little vegetation to cloak the hills and lure you in like mountain forests and tropical jungles. Peering south from the edge of Cody, the skyline is all rock and soil and aridity.

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Hwy 120 not far south of Cody before you begin the climb up a limb of the anticline associated with the Oregon Basin.

As I head south, I enjoy looking for subtle changes in colour and texture, as I try to look for different rock types. I don’t have my geology book or notes for this road section with me this year, so I don’t remember all of the names of the formations, or which formation is where in the landscape. I can pick out the Tertiary Fort Union sandstones that cap the Cretaceous rocks, but I don’t remember the names and stratigraphy (i.e. rock sequence) of the Cretaceous Period. The Fort Union sandstones are the same ones we rode over through much of southeastern Montana – they formed the resistant ridges capped by clinker in some places. I just know the rest of the rocks were laid down in the Cretaceous between 138 and 66 million-years-ago, and you can pick out contacts and different rock types by differences in texture and colour.

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In between the Horse Creek anticline and the Oregon Basin north of Meeteetse. The Absaroka Range is in the background. We are in the shoulder of the Big Horn Basin here; the Absarokas form the basin rim.

We climb up onto the western limb of the Oregon Basin anticline. Off to the east, Elk Butte towers above the surrounding lumpy hills. The axis of the anticline – the centre of an upside-down U-shaped fold in the earth – runs through the edge of the butte. The road needles through the upturned rocks to the west that form tilted cliffs on the flanks of the fold. It is a striking visual reminder that there are tremendous forces at work beneath our feet.

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Looking back north of Meeteetse. I think, but am not sure, that the rock that looks ‘swiss-cheesey’ to the very far right of the picture is the Mesaverde Formation which would make the main slab of tilted rocks the Meeteetse Formation. If anybody knows for sure, please let me know. Both were deposited in the late Cretaceous.

All day today we are riding through the ‘shoulder’ of the Big Horn Basin. The basin is a large oval depression that covers about 10,000 square miles. It is 120 miles long by about 60 miles wide. The basin has three ‘zones’. First, the ‘rim’, consists of high mountain ranges that were thrust up around 60 million years ago during a major mountain-building period of the Rocky Mountain chain. Second, the ‘shoulder’ is an area of anticlines and synclines (folds in the earth) that encircles the basin. It forms a lumpy, bumpy bench between the ‘rim’ and the third ‘zone’, the ‘trough’. The trough is the dry, low centre of the basin.

Today we are riding right along the eastern edge of the western shoulder zone. The shoulder zones on either side of the basin are about five to ten miles wide. As the mountains rose and the basin subsided about 60 million-years-ago, the vertical displacement produced a zone of faults that gave rise to the shoulder. This faulting created all the folds we are weaving through today. The anticlinal folds are not symmetric; they typically have steep sides facing the mountains and gentler sides facing the basin. What this means for a cyclist riding towards the centre of the basin is that there are a lot of steep climbs and long, gentle descents. If you are riding toward the basin edge, you have a series of long, gentle climbs and steep descents. And if you are riding north-south, like we are today, you will find lots of the upturned slabs of rock with steep cliffs facing the mountains and gentle slopes that trail off into the basin centre. Of course it is not as simple as that, but it does explain the excellent, rocky exposures that gently dip to the east which you see along the length of the highway.

The other thing about basins with lots of folds along the shoulder is that those folds trap oil and gas. Even though there isn’t a lot of obvious evidence from the main highway of the industrial nature of the basin – other than all of the oil and gas trucks and company pick-ups with high-vis flags passing by – this basin is a big producer of energy. The basin also produces a lot of bentonite – a clay that has weathered from volcanic ash deposits.

I roll into Meeteetsee to find that the public toilets at the two parks in town have been locked due to vandalism. So I stop at the gas station. Last year, the place had just a teeny, cramped convenience store. But they have done major expansion and it is quite sizeable now. It even has several aisles of food. All I need is the toilet and a drink, but I tell the counter attendant that it’s great to see the expansion from a year ago. She says it has been very well-received by the community and those travelling the long stretch between Cody and Thermopolis.

After a drink break, I go spinning up the steep hill out of town. Cycling route guru and Wyoming resident, John Egan, gave me some suggestions about riding west of town that I had seriously considered. However, the long range forecast is talking about snow in about four days, so I want to get further south before then. So off we go toward Thermopolis.

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More rocks that dip gently east but have a steep western face. I am not sure, but I think the lower brown rock to the far left of the pic might be the Lance Formation (last sequence of rock in the Cretaceous) which is capped by the white/grey Ft Union sandstones (first sequence in the Tertiary).

Last year when I rode this highway going the other direction, the wind was absolutely calm for much of the day. I remember that I really enjoyed this stretch because the rocks were so interesting and the structure of the basin was so obvious. Of course, I was high on cold-medicine and my head didn’t really feel like part of my body that day, but I still remember it being a joyful day. Today, I have an increasing headwind all day, and I am completely sober. But still, I love the range of rocks and the dips and climbs of the road. It’s just as good a second time through.

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More traffic than when I rode this going the other way last year – but it’s a different day of the week, different time of day and early Sept instead of late June. There is a good shoulder the whole way though, so it’s not a problem. Look at the soft, rounded grey shales in the drainage and the harder ridges of sandstone on the horizon.

One of the things I love about the landscape in Wyoming is that, in so many places, it is so direct. It can be in-your-face, but subtle at the same time. If it were a person, and please don’t judge me too much for my anthropomorphism, it would be one of those frank, non-assuming, factual people that don’t mince words but also don’t make judgements. It would be a person comfortable in their own skin with a ‘take it or leave it’ attitude. It would not be a person who succumbed to peer pressure. But it would also be very genuine – not one of those people who say what you want to hear, or say one thing to you and another behind your back. I really like Wyoming. It is an honest and forthright type of landscape that is harsh but subtle, obvious but complex.

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The pines grow preferentially on porous sandstones.
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I love the subtle nature of the landscape in the ‘shoulder’ of the basin.

As we get closer to Thermopolis, the geology gets even more exciting as we start to parallel Cedar Ridge. Bright red Triassic rocks trail along the road for miles. It is a fabulous fold that amazes in its volume and length. We are high in the landscape here before we start the descent into Thermopolis. You can look to the right and see the low, rounded rise of the Owl Creek Mountains off to the right. Off to the left is that superb anticline which lifts those bright red Triassic Chugwater and Jurrasic Sundance formations. Above the bright red rocks, Cretaceous sandstones outcrop in pale greys and whites. It is a diagram of structural geology lifted right out of the drawings of a textbook. It gives me a great thrill because I could not see this going the other way last year (and not just because the site supervisor gave me a lift through lengthy road construction). So not only am I seeing new stuff from a different angle (you get a great view of this from ground level when you ride over the anticline coming into Thermopolis from the north from Worland – which we did last year), but I’m also doing it while riding a fantastic downhill on new pavement with a large shoulder. Yee-ha! It doesn’t take much to get me excited.

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Steep downhill into Thermopolis which sits down in the folds of those rocks. This section was all down to dirt for repaving when I came through here going the other way last year. Off to the right are the lower slopes of the Owl Creek Mountains. Off to the left, sort of left-centre in pic, is a picture perfect anticline with bright red rocks of the Triassic along the axis, flanked by white sandstones of the Cretaceous. The hot springs of Thermopolis are formed when water enters porous rock in the Owl Creek Mountains and filters downslope to be heated at depth. Then, when the water hits the folds of the anticline beneath the ground, the water is forced upward along fractures.

The downhill flings you all the way to the main intersection of downtown Thermopolis. I wasn’t quite sure what to think of Thermopolis last year, and I still don’t know. It feels run-down and neglected in a way. The downtown core is a few blocks long, but it feels like it’s been abandoned for commerce at an interstate exit. Except there is no interstate, and the main highways meet and run straight through downtown. As you head north out of downtown you see a discontinuous line of motels which get progressively younger as you head toward the hot springs. Yet, younger is relative – I think you probably go from the rustic log cabin motor inns from the 1930s up to late 1950s. Similarly, heading south of town, there is a cluster of motels from about the 1950s and 1960s. Then a further blop of newer commerce looks to have sprung up on the far south side of town in the late 1980s or early 1990s. There is a Super 8 and Shopko out there. But it doesn’t look like anything has happened since then, and it looks like most places have never had much of an update. Whatever era in which they were built is the era in which their facades and paint jobs have stayed. It just looks like things have been built but left to bake, freeze and break down in the blasts of wind in a harsh climate. The whole place just feels a bit dishevelled and wind-blown. It speaks of low socio-economic households and a suppression of spirit and progress. I want to like the town, but I just don’t. It is in a spectacular geologic setting. However, even though all of the rocks surrounding town have been uplifted, there is nothing uplifting or upbeat about this town. But it’s a place to lay my head and restock food and water, and sometimes, that’s all a touring cyclist really needs anyway.

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