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Differences Between the Cascades & Rockies

Mar 23rd, 2022

Here at AMLI, we love, love, love our rugged mountain landscapes. There’s a reason so many people are drawn to the snow-capped peaks surrounding Denver or Seattle, and with hundreds of towering mountains looming over both our luxury Seattle apartments and luxury Denver apartments, our residents get to enjoy some truly magnificent landscapes just minutes from their front doors. 

The Cascade Range and The Rocky Mountains are some of the most popular areas for outdoor recreation in the United States, yet they are two completely different ranges formed millions of years apart. 

What are the stories behind our favorite mountains? And how did they come to be? 

How are the Rockies and the Cascades different?

What are the Cascades? 

The Cascades are a range of mountains that extend north to south along the Pacific coast from southern British Columbia in Canada to Northern California. The 700-mile-long range is measured from the Fraser River just North of Vancouver to Lassen Peak just east of Redding in California, measuring as far as 80 miles across in some places and sectioned by a number of rivers in California, Oregon and Washington alike.

The range covers a diverse section of the Pacific Northwest, from wet, rainforest-like conditions in the west to dry, desert-like regions in the east. The western slopes of the Cascades receive significant rain and snow thanks to the prevailing winds and cold water currents from the Pacific Ocean, creating lush forests on the west and significant rain shadows to the east, where vast plateaus carved from ancient floods flattened the landscape and created ideal agricultural conditions. 

Famous mountains in the Cascades include Mount Adams, Mount St. Helens, Mount Baker and Mount Rainier in Washington; Mount Hood, Mount McLaughlin and the Three Sisters in Oregon; and Mount Shasta and Lassen Peak in California, all of which are quite distant from one another, making them all the more impressive to see towering over their hilly surroundings. The highest mountain in the range is Seattle’s very own picture-perfect peak, Mount Rainier, standing at a whopping 14,411 feet above the Emerald City. 

The Cascade Range was named so after the Lewis and Clark Expedition arrived at a section of the Columbia River called the Cascade Rapids, a feature now submerged below the Bonneville Reservoir. The surrounding mountains were known as the “mountains by the Cascades,” which later turned into the “Cascades.”

What are the Rockies? 

The Rockies are not just one of the largest mountain ranges in the United States, but they are the largest mountain system in the entire continent! 

Stretching 3,000 miles from the most northwestern parts of Canada to the sunny center of New Mexico, the range contains extremely diverse regions of ecology and geology, as well as some truly impressive peaks. 

Of the 100 highest peaks in the range, all 100 exceed 12,250 feet in elevation, 62 of them exceed 13,120 feet and 25 of them (all of which are in Colorado) reach over 14,000 feet in elevation. In total, Colorado contains 78 of the highest peaks, followed by Wyoming with 10, New Mexico with six, Montana with three and Utah with just one. Colorado’s Mount Elbert is the highest point in the Rockies at a whopping 14,440 feet. 

The Cree name for these mountains, “Usinnewucheyu, translates roughly to “big rocks,” though the first European description of the current name comes from Canadian Jacques Legardeur de Saint-Pierre who wrote of the mountains in his journal, calling them the “Montagnes des Roche.” Also known as the Rocky Mountains.

How were the Cascades formed?

The Cascade Range was formed bit by bit over 40 million years of volcanic activity, a process that is still continuing to this very day. 

The Cascades are part of a much larger collection of volcanoes known as the Ring of Fire. Though not an officially defined geographic region, the general area stretches along much of the Pacific Ocean’s rim. The 25,000-mile-long belt stretches from New Zealand through Indonesia to Japan and up to Russia’s Kamchatka Peninsula. From there, it turns east and travels along the Alaska coast and south along the Americas right to the southern tip of South America. 

Around 850-1000 volcanoes occupy this region, all of which have been known to be active in the past 10,000 years of Earth’s history. Including, of course, Mount St. Helens, which erupted under 50 years ago.

These volcanoes, including the Cascades, are created as a result of tectonic plates sliding under other plates, forcing magma up to the surface where it spews molten rock onto the surface. Mountain ranges are slowly built up over time as young volcanoes spew debris over the remnants of old volcanoes, creating layer upon layer of volcanic debris that eventually gave us the mountains we have today!

How were the Rockies formed?

The Rockies were also formed as a result of tectonic activity, but with slightly different results. 

The Rockies are much older than the Cascade Range, with formation dating back as far as 80 million years ago during a period of time known as the Laramide Orogeny. This time period saw a great deal of mountain-building in western North America caused by the Pacific Ocean’s Farallon plate moving underneath the North American Plate.

The Farallon plate moved at a shallow angle below the North American plate, breaking up and weakening the ancient bedrock at the very bottom of the plate’s crust above it. The plates were not far enough apart to cause much magma activity, but they were still close enough to cause the crust above to wrinkle and bunch from the movement. The weakened bedrock was forced upward and broke through the softer layers of rock above, creating tall, jagged mountains with steep angles and exposing billion-year-old rock to the surface. 

This is why it’s possible to see dinosaur tracks and fossils on the surface in Colorado, 300 million year-old rocks at Red Rocks Amphitheater and 1.08 billion-year-old granite on Pikes Peak!

Cascades vs. Rockies

Though both the Cascades and the Rockies were formed as a result of tectonic activity on the Pacific coast in the past 100 million years, both mountain ranges felt different effects of that activity. The Rockies were wrinkled and creased into existence like a rug bunching on a hardwood floor, while the Cascades were built layer upon layer over time through a still-going wave of volcanic activity. 

What do they have in common? No matter their formation, location or age, these mountains are home to some of the most beautiful landscapes in the country, and they provide an endless source of recreation and pleasure to us tiny humans who are lucky enough to live near them. 


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Featured photo courtesy Pixabay/jameswheeler

Author of Article

Colleen Ford is a South African who now lives in Spokane, Washington. She loves to travel, camp (in warm weather) and bake.

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