Geology has played a central role in my life since the age of 16, having studied and worked all over the world in and around mining & geology. In 1974 I met and subsequently married Barbara my now wife, also a geologist – the news headline after the wedding was “Marriage on the Rocks”. Now retired we both still have a keen interest in the subject wherever and whenever relevant, are members of the Geologists’ Association and often go on our own and organised field trips.
Whilst working I regularly visited mining operations across North America but still had some personal unfinished geological business in the country which had hitherto eluded me. Therefore in 2016 Barbara and I undertook something of a geological pilgrimage to see the Grand Canyon and other iconic sites in Arizona and Southern Utah. Notwithstanding, the USA is a big place with many other remarkable geological locations to see, so we recently set out on an extensive road trip through Wyoming, Montana, Utah and Colorado. Naturally Yellowstone National Park was central to our plans but there was much, much more to see.
Given such a route the trip inevitably contained three main themes: dinosaurs, volcanic activity and plate tectonics. Other than Yellowstone, we were less interested in conventional tourist attractions but more on the lesser known geological sites within these western states. Whilst planning for the trip we came across the excellent Roadside Geology series of books (see Maps-Stats-Stuff section), which became an indispensable aid during the trip, helping to bring to life and provide insight into the geology and scenery as we passed through; I’ve long thought such books would be a great idea for the UK and have even thought of writing one – watch this space!
Arriving in the USA from the UK into Denver, the first few days required driving some 600-miles across Wyoming to reach Yellowstone. To most Wyoming might seem somewhat empty and devoid of interest at first glance but to a geologist it is one of the world’s premier locations. Although the least populous state in the USA, Wyoming is renowned for its abundance of dinosaur fossils and vast oil fields, so our drive to Yellowstone would be anything but boring.
Since first travelling to the USA I have been smitten by the vast open spaces that dominate much of the interior and on this trip we were to traverse many miles of such areas but first stop was a visit to the University of Wyoming Geological Museum (see above) in Laramie. Coming from London and having visited many of the world’s larger cities I am accustomed to parking difficulties but Laramie easily surpasses them all. After more than an hour driving around in circles we gave up, checked-in at our hotel on the outskirts of town and, with some further difficulty, took a taxi back to the museum; Laramie seriously needs to address car parking if it wants to attract visitors!
Despite the aforesaid difficulty, the visit to the museum was well worth it. Of course, being in Wyoming the collection of dinosaurs (sse picture above) and numerous other paleontological marvels was outstanding but looking around the adjacent corridors of the geology department there was also much else of interest. The museum sits at the heart of an impressive geoscience complex that would be the envy of any British faculty, which includes the geology department and research facilities, the state geological survey, Earth Sciences and the Bureau of Mines.
Heading out the next day from Laramie en route to Thermopolis via Casper, we were treated to an enthralling example of America’s magnificent desolation at its best along the US30 road (see above). Rich brown grass glowed in the early morning sun, cloaking the rolling hills which stretched in all direction as far as the eye can see, interrupted only by the tarmac of our road following the adjacent rail line and accompanying phone lines, all disappearing into the distant horizon.
After about 50-miles we stopped to enjoy the aforesaid views and investigate the famous Como Bluff, location of major dinosaur discoveries and paleontological feuds in the late 19th Century. The site has apparently been largely emptied of its dinosaurs, now on display in major museums throughout the world but there remains by the roadside a cabin (see above) built entirely of dinosaur bones! Shortly thereafter the US487 crosses the interesting Flat Top anticline just north of Medicine Bow, before continuing into the southern area of the prolific oil bearing Powder River basin and the town of Casper.
Rolling into Thermopolis later that day the town’s charm was immediately obvious. An important center for the early settlers heading west in the 19th century, the small town is founded around hot geothermal springs that emanate along a deep fault line. Apart from being our night’s stopover, Thermopolis is home to the Wyoming Dinosaur Center, which to our surprise probably outshone the exhibitions at Laramie of the previous day. The dinosaur and many other exhibits were simply outstanding – beautiful quality, numerous and well documented (see above).
Other than visiting the various geological sites and museums along the way, we chose this particular route in order to enter Yellowstone Park via the 10,947ft Beartooth Pass from Montana and the Silver Gate entrance. Throughout our trip we experienced outstanding weather – warm / hot clear days and cool nights – except for the day planned to cross the Beartooth, which was closed due to heavy snow. In some compensation, the route on the Chief Joseph Highway, which passes through terrain of over 8,000ft in places, provided wonderful geology and scenery as an alternative access to the Northeast Entrance where it was still snowing when we arrived.
Yellowstone National Park
Yellowstone Park is located over one of the world’s largest so-called super volcanoes, which is a caldera that erupted three times during the past 2.1 million years as the area transits northeast over a geological hot spot. It could erupt again but for the period of our visit it just continued to belch out steam and hot water from a number of vents and geysers.
Compared to the Taupo – Rotorua super volcano which we visited in New Zealand, the geothermal activity at Yellowstone is probably more extensive and certainly more active. Of course Old Faithfull (above) is the big crowd puller but we enjoyed many of the smaller features, such as White Dome Geyser found on the Firehole Lake Drive (below).
The other geological highlight of the Park was the view of the Grand Canyon of Yellowstone from Artist Point, located just south of Canyon Village. At this point the Yellowstone River drops precipitously over a resistant band of rhyolite, before subsequently cutting deep into the adjacent highly altered and brightly coloured volcanic rocks that approximately follow the northern edge of the caldera (below).
The downside of Yellowstone, like so many other international tourist attractions (such as London), are the large crowds that populate almost every stop and block up the roads – I hate to think what the high season from June to August must be like! In compensation, the non-human life in the Park was excellent.
I’d previously thought a sight of Bison would be quite unusual but we were treated to many views of these magnificent animals, sometimes a little too closely as they wandered onto the park roads and ambled past cars! Elk and deer were also prevalent as were eagles and cranes. Notwithstanding, I probably expected more wildlife, which I suspect had wandered off into the hills to get away from the aforementioned crowds.
Grand Teton National Park
We obtained our first sight of the Teton mountain range from the northern end of Jackson Lake (above) and frankly couldn’t stop looking at them until we moved on two days later. Extending over some 40 miles in length from north to south and up to 13,775ft in height, the magnificence and beauty of these mountains cannot be overstated but for me the story of their origin is literally jaw dropping.
The Tetons are mostly a mix of sediments and metamorphic rocks, which over the past six to nine million years has been thrust upwards along a normal fault line, the western up-thrown block forming the current Teton Mountain Range. Total vertical movement on the fault during this time is some 33,000ft. With 7,000ft currently seen above ground, this means that the eastern (down throw) side of Jackson Hole must be filled with about 26,000 feet of sediments – mindboggling! Whichever view is taken of the Teton Range the mountains remain beautiful and quite mesmerizing. However, at 10,450ft, from the top of the Jackson Hole Tramway their majesty takes on a different perspective (see below) and a better view of the geology; however, at £30 per person we won’t be heading up the tramway again in a hurry!
As we finally turned our back on the Tetons to head south, we were left with a feeling that the trip had already peaked (no pun intended) and what was to come would be something of an anticlimax, which fortunately could not have been further from the truth.
Fossil Butte National Monument
Where possible I prefer to travel on the more minor back roads in the USA in order to get a better feel for the country and had expected the drive on such roads from Teton Village to Kemmerer would be nothing more than a transit passing through barren, somewhat uninteresting country. However, shortly after leaving from the south of the cowboy town of Jackson, our route turned east on the US191 and entered the dramatic Hoback River Canyon, which cuts through a complicated array of overthrust faults and folds that are part of the substantial +11,000ft Gros Ventre & Wind River Mountain Ranges. The scenery here was dramatic and made all the more attractive by the early fall colours of the Aspen trees which lined the canyon’s twisting route though the canyon like sentinels.
Progressing south beyond the Hoback River into cattle country, the views expanded and the landscape became gradually more arid. Then shortly past Daniel Junction on US189, our attention became inexorably drawn eastwards where over 80 miles away, the snow-topped Rocky Mountains spanned the horizon over a length of at least 120 miles. This striking view held great promise for later in the trip when we would cross the Rockies in Colorado but for now Kemmerer and subsequently Utah beckoned.
Fifty two million years ago, three great lakes covered the much of the areas of present day Wyoming, Utah and Colorado. The sediments deposited in these lakes created the Green River Formation, which now consists of fossil rich beds of limestone, mudstone and volcanic ash. The smallest of these Fossil Lake (60 x 40 miles) was situated just west of Kemmerer and as a result of a unique depositional environment at the time, is today home to some of the world’s most exquisite fossils, in particular fish, insects, plants, birds and crustaceans, which are found beautifully preserved along the thin bedding planes of the aforementioned rocks. In addition to the excellent National Park museum at Fossil Butte, local individuals own and continue to exploit numerous small hillside quarries throughout the area in order to sell specimens.
Such is the vastness of the USA I’d never heard of the Uinta Mountains, which are Precambrian in age and located between Salt Lake City in the west and Vernal in the east. Faulted along its north and southern margins, the Uintas are one very large east-west anticline. At some 100 miles in length and rising to 13,528ft, the range is significant and driving south across the eastern section on the range we were able to see some dramatic geological sections exposed and beautiful related scenery.
Flanking the north side of the Uinta Mountains, south of Manila just across the border into Utah, the 9-mile Sheep Creek road loop provides outstanding views of the geology. In particular, structural sections along the North Unita Fault are well exposed, which separates Precambrian Unita sandstone rocks from the Mississippi Madison Limestone, producing some truly sensational views – see above and below.
Shortly thereafter just north of the US44 road at the Red Canyon Visitor Center, the Green River flows south from the Wyoming hills into Flaming Gorge, meanders through the Horseshoe and Kingfisher Canyons, crosses the North Uinta Fault and then enters the Red Canyon. The Flaming Gorge Dam is part of the very large Colorado River Storage Project built between 1958 and 1964 and the views looking into the aforementioned Canyons from the southern rim are truly amazing (see below).
Continuing south on US191 towards Vernal, the route then crosses Mesozoic and Palaeozoic sedimentary rocks that were tilted by the rising Uinta Mountains to form a prominent series of cuestas – erosion resistant ridges (hogbacks) separated by valleys of softer rock.
Dinosaur National Monument
Covering an area of 330 square miles, the Dinosaur National Monument park straddles the Utah and Colorado border. The monument contains one of the richest known dinosaur fossil beds from the Jurassic era, discovered in 1909 by Earl Douglas from the Carnegie Museum, Pittsburg. Following discovery the main dinosaur bearing strata have over time been exposed by quarrying to produce one of the most incredible geological features I have ever seen.
Dipping steeply south, the main fossil bearing strata extends approximately east-west for about one quarter of a mile. Since the original discovery bones from more than 500 individual dinosaurs have been collected, as well as thirteen full skeletons which are now exhibited at major museums throughout the USA. The park was formed in 1915, then in 1957 the central 600ft x 40ft main fossil bearing section was roofed over to form an exhibition hall, where some 1,500 dinosaur bones can now be seen still in situ. Frankly I could not even have imagined such a place even existed, which was absolutely breathtaking and probably the most extraordinary geological highlight of the tour, a trip which contained no shortage of other significant highlights.
Approximately 3-miles east of the Quarry Center the Spilt Mountain anticline is spectacularly exposed from erosion by the Green River, which now gently meanders through the folded rocks along the southern flank of the mountain. This was personally one of my favourite locations in the park and we returned later in the evening to view the area under the clear, dark skies of night and image the Milky Way.
Subsequently a long drive into the heart of the park at Harpers Corner provided extraordinary views of tightly folded structures along the Green River further upstream, as well as distant easterly vistas of the Yampa River, where it is deeply incised into Pennsylvanian limestone and sandstone beds.
The Rocky Mountains
Shortly after leaving Vernal heading east on the US40, we crossed the border back into Colorado for the final leg of the road trip. Inevitably after the leaving the Dinosaur National Monument behind, the scenery on the journey to Steamboat was somewhat more prosaic in nature, though not without some interest. Approaching Steamboat and beyond all that changed as various geological features associated with a plate boundary collision became all too evident in the shape of the Rocky Mountains.
Having missed driving over the Beartooth Pass route into Yellowstone because of snow, I was anxious about finding similar conditions on the Trail Ridge Road, which goes from Granby to Estes Park and at 12,183ft, is the highest paved road in North America. Since leaving Yellowstone Park snow had returned across the area but the weather now in the Rockies was clear blue sky and the drive over the pass did not disappoint – though it was very, very windy on top (+100 mph) and the lack of oxygen at that height was very noticeable; most of the trip varied between 6,000 and 8,000ft (even Denver is known as the Mile High City) and I was looking forwards to getting back to lower altitude on returning home and some nice thick, oxygen rich air!
I’ve been to the Colorado Rockies a number of times before and even skied at Winter Park but the relaxed time spent in and around the Rocky Mountain National Park at fall, was still an interesting and very enjoyable time. Its proximity to Denver inevitably means it’s busy but the scenery and geology remains the same – spectacular.
From Estes we drove directly south on US7, which skirts the eastern edge of the Rockies and stopped at Nederland. Located at the north end of the Southwest – Northeast trending Colorado mineral belt, Nederland was founded on mining – gold, silver & tungsten – and we therefore had to visit the local mining museum; mining is no longer carried out here or along most of the trend.
On the final day en route to the airport, we just had to stop off at the Dinosaur Ridge area just outside Denver, south of Golden. Complete dinosaur skeletons were discovered within a fine-grained but hard sandstones in the late 19th century, the Morrison Formation, which being highly resistant forms north-south trending hogback features across the area. Nearby at Dinosaur Ridge, numerous dinosaur footprints have been preserved within algal mats lying on the sandstone bedding planes – a few hours later we were at 35,000ft heading home!
In April 2016 we undertook a geological tour of the USA taking in the Grand Canyon, Monument Valley, Bryce Canyon and Zion National Park. I was deeply moved by the Grand Canyon and very impressed by the other locations too – USA geology takes some beating. I thought that would prove to be the pinnacle of USA geology but this year’s trip has at least equaled if not exceeded it. My wife is the paleontologist in the family and I’m more interested in structure and igneous / volcanic / metamorphic areas. However, all such features and more were exceptionally well represented throughout this trip, which was made all the more wonderful by the early fall colours.
However, it was the Quarry Center at the Dinosaur National Monument and the surrounding areas that literally blew me away – who would think such a place could even exist? In the correct sense of a now much overused word, this trip had been been truly awesome.
Stats – Maps – Stuff
Tour: 17th September to 6th October 2019, 20-days
Total Mileage: 2,400 miles
Maps: Michelin Map-172- Big Sky Country – Idaho, Montana, Wyoming, Utah & Colorado 1: 1,267,200 or 1” = 20 miles
GTRMapping.com – Yellowstone & Grand Teton National Parks & Adjacent Areas 1” = 4-miles
National Park Service (US Department of the Interior): Yellowstone, Grand Teton, Fossil Butte National Monument, Dinosaur national Monument, Rocky Mountain National Park
Mapps.me app for offline maps
Roadside Geology of (1) Wyoming (2) Yellowstone (2) Utah (3) Colorado, published by Mountain Press Publishing Company
+ Windows Into The Earth – The Geologic Story of Yellowstone and Grand Teton National Parks by Robert B. Smith & Lee J. Siegel, published by Oxford University Press
|1||Tuesday 17thSept||10||Denver||Flight & Drive|
|155||Denver to Laramie||Wyoming Geology Museum|
|270||Laramie to Thermopolis||Dinosaur Museum|
|4||Friday 20th Sept||150||Thermopolis to Red Lodge||Via Cody|
|180||Red Lodge to West Yellowstone||Via Chief Joseph Highway and Mammoth Hot Springs|
|6||Sunday 22nd Sept||?||Yellowstone||Norris-Canyon Village-West Thumb Loop|
|7||Monday 23rd Sept||?||Yellowstone||Old Faithfull + Midway Geyser Basin area|
|8||Tuesday 24th Sept||130||Yellowstone to Teton Village||Jackson Hole Cable Car|
|?||Grand Teton||Jenny Lake|
|10||Thursday 26th Sept||170||Teton Village to Kemmerer|
|11||Friday 27th Sept||?||Kemmerer||Fossil Butte National Monument|
|Saturday 28th Sept||155||Kemmerer to Vernal||Flaming Gorge|
|13||Sunday 29th Sept||?||Dinosaur National Monument||Quarry Center|
|14||Monday 30th Sept||?||Dinosaur National Monument||Colorado – Harpers Corner|
|15||Tuesday 1st Oct||160||Vernal to Steamboat Springs|
|140||Steamboat Springs to Estes Park||Via Trail Ridge Road|
|17||Thursday 3rd Oct||?||Estes Park||Bear Lake etc|
|60||Estes Park to Boulder||via Nederland & Boulder Canyon|
|19||Saturday 5th Oct||70||Boulder to Denver + fly home||Via Dinosaur Ridge|
|20||Sunday 6th Oct||Arrive home|