For starters, the two are significantly different in size: the Rocky Mountains stretch 3, miles from the Yukon Territory to New Mexico. The Cascade Range, by comparison, is less than one-fourth the length of the Rockies and considerably narrower. Cascade Mountains. Type: mountain. Location: North America. Much of the NWCS domain was eventually eroded away, exposing the oldest rocks at the bottom of the thrust package.
The Chuckanut Formation was deposited on top of this thrust package, and the entire sequence of rocks was later intruded by volcanoes and plutons. The Cascade Crystalline Core Domain rocks are made up of the accreted terranes of the Insular and Intermontane belts as well as oceanic rocks, continent-derived rocks, and rocks that formed in the ancient volcanic arc.
Beginning about 90 million years ago, all of the rocks in the Cascade Crystalline Core Domain were metamorphosed due to deep and prolonged burial. These rocks make up some of the most beautiful alpine scenery in all of Washington. These terrains vary in rock type metamorphosed oceanic rocks, arc volcanics, sediments, pieces of the mantle, and old continents , and each original rock type has a different age ranging between and million years old!
Many plutons were intruded into the buried and accreted terranes during metamorphism, such as the Mount Stuart Batholith. The intruding magma supplied some of the heat that was needed for recrystallization and metamorphism. This domain is composed of the Methow stratigraphic sequence and the Hozomeen Group. The Methow Basin Domain originated on the ocean floor between and million years ago. The ocean floor was made of layers of basalt, sandstone, mud, chert, and other sediments that were eroded off the continent into the ocean.
The sediments and basalt were subsequently uplifted, and faulted, and thrust eastward in a series of fault-bend folds. The Cascade Arc has been erupting a chain of volcanoes over the last 40 million years along the crest of the modern day Cascade Range. The South Cascades record this older period of volcanic eruption, as most of the rocks exposed there are from this time; the extensive Ohanapecosh Formation is a good example of this.
The volcanoes that erupted in the North Cascades during this time period have been eroded away because the North Cascades are being uplifted at a greater rate than the south Cascades. However, the plutonic roots of these ancient volcanoes remain, and they outcrop as numerous large batholiths such as the Chilliwack batholith, the Snoqualmie batholith, and the Cloudy Pass pluton.
Cascade volcanism began within the last 5 to 7 million years, and the modern-day volcanic arc is still active, extending from Mount Garibaldi in British Columbia in the north to as far south as Mount Lassen in California. Mount Baker is a stunning, glacially covered, 10, feet tall, very young geologically speaking volcano.
The most recent eruption of Mount Baker was in , although there were signs of unrest and fumarole activity in Steam and gas still issue from both Sherman Crater and the Dorr fumarole field on the northeast flank of the volcano today. The High Cascades dominate the landscape and contain the tallest active and dormant volcanoes in the region.
In fact, over the last several hundred years, all significant eruptions in the contiguous United States have come from Cascade Volcanoes. The eruption of Mount Saint Helens is considered the most significant eruption to occur in the contiguous United States and was preceded by two months of earthquakes. The highest peak in the Cascades and tallest in the state of Washington is Mount Rainier. At 14, feet, Mount Rainier is considered one of the most dangerous volcanoes in the world due to its incredible amount of glacial ice and proximity to Seattle, a highly populated metropolitan area.
The North Cascades, located north of Mt. Rainier , contain mostly high peaks of non-volcanic origin, but also include stratovolcanoes like Mount Baker and Glacier Peak located in the Cascade Volcanic Arc.
Mount Baker and Glacier Peak are the only summits that exceed 10, feet in the North Cascades and are generally the most popular peaks for climbing. Although only two peaks exceed 10, feet, several summits in the North Cascades exceed 9, feet and are characterized by dramatic, rugged topography. Anderson, James. Explore the origins of Sea to Sky Country. The edge of wilderness where oceans and mountains meet. A perfect gift all year-round. Uncompromising and unforgettable.
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