Cascade Volcanoes Facts & Worksheets

The Cascade Volcanoes are a chain of volcanoes located in the western part of North America, extending from northern California through Oregon and Washington and into southern British Columbia, Canada. These volcanoes are part of the larger Cascade Range, which is a segment of the Pacific Ring of Fire.

See the fact file below for more information on the Cascade Volcanoes, or you can download our 26-page Cascade Volcano worksheet pack to utilize within the classroom or home environment.

Key Facts & Information

HISTORY

• The geological history of the Cascade volcanoes spans millions of years and is marked by a series of volcanic eruptions, lava flows, and other geologic events.
• The origins of the Cascade Range can be traced back to about 40 to 50 million years ago during the Eocene epoch. The region was tectonically active as the Juan de Fuca Plate started to subduct beneath the North American Plate, leading to the uplift and deformation of the crust.
• Between 37 and 5 million years ago, a series of volcanic arcs developed along the western edge of North America as a result of the ongoing subduction.
• These ancestral Cascade Volcanoes were composed of basaltic and andesitic lavas, and played a significant role in building the foundation of the modern Cascade Range.
• Following the formation of the ancestral Cascade Volcanoes, a period of erosion and uplift occurred due to various geological processes, including weathering, glaciation, and tectonic forces. 
• This phase helped shape the landscape and exposed the volcanic rocks that would later be covered by subsequent eruptions.
• Around 2 to 3 million years ago, a renewed period of volcanic activity began, giving rise to the modern Cascade Volcanoes. 
• This phase involved the eruption of more silica-rich magma, resulting in the formation of stratovolcanoes characterized by their steep slopes and explosive eruptions.
• Some of the Cascade Volcanoes have undergone catastrophic eruptions that resulted in the collapse of the central volcanic edifice, forming large calderas. 
• The most notable example is Crater Lake’s Mount Mazama, which experienced a massive eruption around 7,700 years ago, leaving behind a caldera that eventually filled with water to become Crater Lake.
• The Cascade Volcanoes have remained active into modern times. 
• Notable eruptions include the catastrophic eruption of Mount St. Helens in 1980, which resulted in the collapse of its northern flank and the release of a devastating pyroclastic flow. 
• Mount Rainier, Mount Hood, and other volcanoes in the range have also experienced eruptions within the past few centuries.
• Throughout this geological history, the Cascade Volcanoes have had a significant influence on the surrounding environment. They have shaped the topography of the region, contributed to the formation of fertile soils, influenced the hydrology of river systems, and provided unique habitats for plant and animal life.

GEOLOGY

•  The geology of the Cascade Volcanoes is closely tied to the tectonic activity along the western edge of North America, where the Juan de Fuca Plate is subducting beneath the North American Plate. 
• This subduction zone is responsible for the formation of the Cascade Volcanoes.
• The Cascade Volcanoes are stratovolcanoes, also known as composite volcanoes, which are characterized by their steep slopes and explosive eruptions. They are built up over time by alternating layers of lava flows, pyroclastic deposits (such as ash and pumice), and volcanic debris. The eruptions of Cascade Volcanoes can be highly explosive due to the high silica content of the magma, which leads to the formation of viscous lava that traps gases, building up pressure until it is released explosively.
• The magma feeding the Cascade Volcanoes is generated by the subduction of the Juan de Fuca Plate beneath the North American Plate. 
• As the oceanic plate descends into the mantle, it heats up and releases volatiles (such as water and carbon dioxide) from hydrated minerals. These volatiles rise into the overlying mantle wedge, reducing the melting point of the mantle rocks and generating magma.
• The magma generated in the mantle rises to the surface through fractures and conduits, forming volcanoes along the Cascade Range. As the magma ascends, it may encounter obstacles, such as cooler rocks or a solidified magma chamber, causing it to stagnate and potentially trigger explosive eruptions.
• Notable Cascade Volcanoes include Mount St. Helens, Mount Rainier, Mount Hood, Mount Shasta, and Crater Lake’s Mount Mazama. Each volcano has its own unique geological history and characteristics, but they all share the common origin of being part of the Cascade volcanic arc.
• In addition to explosive eruptions, Cascade Volcanoes can also produce other volcanic hazards, including lahars (mudflows), pyroclastic flows, ashfall, and volcanic gases. 
• These hazards pose risks to nearby communities and infrastructure, making the monitoring and study of Cascade Volcanoes important for hazard mitigation and public safety.

NOTABLE ERUPTIONS

Mount St. Helens (Washington, USA):

• May 18, 1980: Mount St. Helens experienced a catastrophic eruption, which resulted in the largest debris avalanche in recorded history. 
• The eruption removed the volcano’s northern flank, triggered a massive lateral blast, and produced a devastating pyroclastic flow. The eruption caused the death of 57 people, destroyed hundreds of square miles of forest, and caused significant damage to infrastructure.

Mount Rainier (Washington, USA):

• 5,600 years ago (approximate date): Mount Rainier had a major eruption known as the Osceola Mudflow. It generated a large volcanic mudflow that traveled down the White River valley, reaching as far as the Puget Sound lowlands.
• Around 1,000 years ago: Mount Rainier experienced the Sunset Crater eruption, which resulted in the formation of a large crater on the volcano’s summit and the release of pyroclastic flows.

Mount Hood (Oregon, USA):

• Late Holocene (last few thousand years): Mount Hood has had multiple eruptions, including the most recent around 220 years ago. These eruptions produced pyroclastic flows, lahars, and lava flows.

Mount Shasta (California, USA):

Late Pleistocene (around 9,500 years ago): Mount Shasta experienced a large explosive eruption, which produced the Hotlum Cone, a prominent lava dome.

• 1786: Mount Shasta had an eruption that produced a significant ashfall and pyroclastic flows.

Crater Lake’s Mount Mazama (Oregon, USA):

• Around 7,700 years ago: Mount Mazama had a massive eruption that resulted in the collapse of the volcano’s summit, forming a caldera. This eruption, known as the Mazama eruption, was one of the largest volcanic events in North America’s history.

CASCADE’S MOST NOTABLE VOLCANOES

• Here is a list of some prominent Cascade Volcanoes, along with their approximate heights:
  • Mount Rainier (Washington): 14,411 feet (4,392 meters)
  • Mount Shasta (California: 14,179 feet (4,322 meters)
  • Mount Adams (Washington: 12,281 feet (3,743 meters)
  • Mount Hood (Oregon): 11,249 feet (3,428 meters)
  • Mount Baker (Washington): 10,781 feet (3,286 meters)
  • Glacier Peak (Washington): 10,541 feet (3,213 meters)
  • Mount Jefferson (Oregon): 10,495 feet (3,199 meters)
  • Three Sisters (Oregon, USA):
    • South Sister: 10,358 feet (3,157 meters)
    • Middle Sister: 10,047 feet (3,063 meters)
    • North Sister: 9,085 feet (2,769 meters)
  • Mount McLoughlin (Oregon): 9,495 feet (2,894 meters)
  • Lassen Peak (California): 10,457 feet (3,187 meters)

Cascade Volcano Worksheets

This fantastic bundle includes everything you need to know about the Cascade Volcanoes across 26 in-depth pages. These ready-to-use worksheets are perfect for teaching kids about the Cascade Volcanoes. These volcanoes are part of the larger Cascade Range, which is a segment of the Pacific Ring of Fire.

Complete List of Included Worksheets

Below is a list of all the worksheets included in this document.

1. Cascade Volcanoes Facts
2. Vocabulary Check
3. Mapping the Cascade
4. Stratovolcanoes
5. Notable Volcanoes
6. Mount St. Helens
7. Volcanic Legend
8. The Three Sisters
9. Volcano Watch
10. Promoting the Cascade
11. Local Stratovolcano

Frequently Asked Questions

What are Cascade volcanoes?

Cascade volcanoes are a chain of stratovolcanoes located in the western part of North America, extending from British Columbia in Canada through Washington, Oregon, and into northern California in the United States. They form part of the Pacific Ring of Fire.

Which is the most well-known and active volcano in the Cascade Range?

The most famous and active volcano in the Cascade Range is Mount St. Helens. It is located in Washington State and gained worldwide attention due to its catastrophic eruption in 1980, which resulted in the loss of lives and significant destruction of the surrounding area.

How do Cascade volcanoes differ from other types of volcanoes?

Cascade volcanoes, also known as stratovolcanoes or composite volcanoes, are characterized by their steep-sided conical shape and explosive eruptions. They are built by alternating layers of lava, ash, and other volcanic materials, which give them their distinctive appearance.

Are all Cascade volcanoes active?

While the Cascade volcanoes have a history of volcanic activity, not all of them are currently active. Some of the notable active volcanoes in the Cascade Range include Mount St. Helens, Mount Rainier, Mount Hood, and Mount Shasta, among others. However, others, like Mount Jefferson and Mount Bachelor, have not erupted in recent times.

What are the potential hazards associated with Cascade volcanoes?

Cascade volcanoes pose several hazards, including explosive eruptions, pyroclastic flows (fast-moving currents of hot gas and volcanic material), lahars (mudflows resulting from melted snow and ice mixing with volcanic debris), and volcanic ash fall. These hazards can have significant impacts on human populations, infrastructure, and the environment in the surrounding areas.

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