Rising from the interior plains of the United States and Canada, one of the largest mountain ranges in the world extends across the west of the North American continental shelf. Covered in breathtaking mountains and valleys, which invite outdoor lovers to hike, climb, ski and camp among the thousands of snow-covered peaks and vast glaciers, the Rocky Mountains have countless stories to tell. To get to the bottom of them, in this article, we will take a closer look at its geographical extent, what kind of secrets lay within the mountain range, and how it determines the fate of all water falling on the continent. To get a better understanding of the area we are talking about, we will start with.
Chapter 1: Physical Geography
Rocky Mountains Rising from the harsh Antarctic Ocean in the far south of the Americas, begins the American Cordillera, the largest and longest interconnected mountain system in the world. Containing the Andes of South America, the Central American Ranges, and the Sierra Madres of Mexico, the American Cordillera slowly transitions into the Rocky Mountains after entering the contiguous United States in New Mexico. From there, a collection of over 100 smaller mountain ranges merges together into a dense network of summits and valleys, what we today call the Rocky Mountains.
The definition of where the Rockies begin and end is often debated among geographers and it primarily depends on which governmental body you ask. One thing everybody can agree on is that the range starts north of the Pecos River in New Mexico, but the northern border is more ambiguous. Canada for example defines the northern end of their slice of the Rockies with the Liard River, while the US occasionally extends this line to the Alaskan Brook Mountains which they designate as being a part of the Arctic Rockies. we will go with the Canadian definition, limiting the northern boundary to the Canadian Provinces of Alberta and British Columbia. In BC, a slipping fault line has created a deep valley called the Rocky Mountain Trench, which narrows the Rocky Mountains to its thinnest width, only spanning around 100 kilometers of 60 miles from east to west. Upon entering the US states of Idaho and Montana, the elevated region widens to its farthest extent, spanning almost 600 kilometers or 370 miles across Wyoming and Utah, before narrowing again in Colorado and New Mexico. The whole eastern flank of the Rockies is bordered by the Interior Plains of Canada and the US, from where the mountains immediately reach their highest peaks in the South. Compared to the valleys of the plateau, the Rocky Mountain Peaks typically rise over 2000 meters or 6500 feet above the surrounding landscape, with the highest peaks touching the 4400 meter or 14400 feet mark.
Across the whole 4800 km or 3000 mile long north-south extent, the mountains share many similarities in geological features, being prime destinations for mountaineering and outdoor retreats, yet the three main sections all have their unique features as well, bringing us to.
Chapter 2: Inside the Rocky Mountains
he Canadian Rockies between the Canadian Prairie and the Rocky Mountain Trench are the birthplace of many of Canada's greatest rivers with the Columbia, Fraser, North Saskatchewan, Athabasca, and Bow River all originating in this relatively thin strip of mountains. The Canadian Rockies are covered in 5 National Parks which through the resort town Banff constitute one of Canada's most popular tourist destinations. 4 million tourists visit Banff and its adjoining National Park annually, enjoying the pristine mountains, rivers, glaciers, and lakes for various outdoor activities from skiing to hiking all year round. These mountains are particularly known to have a lot of dry snow, which is perfect for powder skiing. Crossing the border to the United States, we enter an even more famous nature spectacle with the oldest National Park in the world.
Yellowstone, which sits right in the heart of the Rocky Mountains has fascinated hikers and explorers since the dawn of humans on the continent, but it wasn’t always meant to be a National Park. If it weren’t for a group of dedicated nature-loving men in the 1860’s and 70’s, this region, and many other pristine natures may have looked completely different today.
The park as a whole is characterized by its volcanic origin with a massive magma plume under the continental shelf, which is currently filling up an enormous magma chamber.
According to the US Geological Survey, this chamber has emptied itself three times in the past 2 million years, at intervals between 800 and 660 thousand years. Considering that the last eruption was 640 thousand years ago, some are afraid that the next one is overdue, but the USGS sees no reason to worry. Firstly, a series of 3 entries is not sufficient to make any predictions. Further, the scientists expect minor hydrothermal eruptions to occur as a precursor of Yellowstone's next big lava eruption, and these haven’t occurred yet. And just to clarify, with “minor hydrothermal eruptions", the scientists mean explosion craters with a diameter of half a mile, so the water fountain of the Old Faithful does not count.
The fear-inducing mantle plum responsible for the large caldera is also responsible for a whole array of other volcanic features that make Yellowstone so popular. Over 10.000 such features ranging from geysers and mud pods to hot springs can be found in the region in and around Yellowstone. Compared to the rest of the world, this includes a staggering 62% of all such features currently discovered globally. Continuing the Rocky Mountains further south, we enter the states of Colorado and Utah, which encompass the most elevated region of this journey. Here, a total of 53 peaks with a height of over 4200 meters or 14.000 feet can be found, more than in any other US state. This list of mountains is called the “Fourteeners” and is often taken up as a challenge by mountaineers to summit all of them, similar to the 7-summit challenge of climbing the tallest peak of each continent. The highest density of tall mountains and generally elevated land actually makes Colorado the state with the highest average elevation across the US, despite almost 50% of the state being covered by the interior plains without any significant topographical features.
Looking back north from New Mexico to the northern border of British Columbia, the whole length of the Rocky Mountains covers some of the most exciting nature of the American continent, being a go-to place for outdoor and winter sports enthusiasts. Next to these groups of people, it is also very interesting place for the study of hydrology, bringing us to.
Chapter 3: The Continental Divide and its peculiarities
Any raindrop falling anywhere on any of the American continents will eventually either drain into the Atlantic or the Pacific Ocean. Which of these oceans it will be, depends on which side of this invisible line the raindrop will fall on. Stretching from the most southern tip of Tierra Del Fuego all the way up to the Seward Peninsula in Alaska, a continuous line called the Continental Divide of the Americas separates the continent into two basecamps.
This line typically connects the tallest peaks of the continent, which within the continental US and Canada means it goes right through the heart of the Rocky Mountains. Like with anything in the world, however, the exceptions proof the rule, and exceptions there are a few. Firstly, there are several basins spread around the continent where water is enclosed my mountain ranges and trapped until it is evaporated, leading to many of the salt flats in Utah and Bolivia.
These endorheic basins are by far not the most uncommon thing though, since about 20% of all continental areas do not drain into an ocean. More peculiar are the Isa Lake in the Yellowstone National Park and Committee's Punch Bowl, a small mountain lake on the border between Alberta and BC, which during over flooding have outlets on both sides of the continental divide, meaning the same lake drains into both oceans. The biggest exception to this rule, however, and the only river in the world that spreads its flow almost equally into two of the world's oceans is the North Two Ocean Creek.
In the Teton Wilderness on the western side of the continental divide, the creek flows through a narrow gorge, slowly approaching a perpendicular valley. The gorges' topography closes in on the imaginary continental divide line and just as the waters are close enough, one particular rock outcrop exactly on the continental divide perfectly splits the stream into two. If a water droplet happens to be towards the western stern side of the creek, it will be guided through the Snake and Columbia Rivers into the Pacific Ocean, whereas the eastern side of the narrow creek is a tributary to the Yellowstone River, which drains into the Missouri River, and finally the Mississippi river to reach the Gulf of Mexico and eventually the Atlantic Ocean. This pass also allows fish species from one half of the continental divide to migrate to the other half, which before its discovery has puzzled scientists for decades.
For some reason, Yellowstone Lake hosted a specific trout species, identical to one otherwise only found in the upper tributaries of the Snake River. The journey across the North Two Ocean Pass is still found to be a complicated and unlikely endeavor, but the inclusion of occasional floods from the end of the last ice age finally shed light on the mystery. This quirk finishes up our journey across the Rocky Mountains and I hope you learned something new about the most spectacular mountain range of North America.