1. The Cascade Range: This range extends from Northern California into Oregon and Washington. The volcanoes in this area are part of the Cascade Volcanic Arc, formed by the subduction of the Juan de Fuca Plate under the North American Plate. Some notable volcanoes in this region include:
* Mount Shasta: The second-highest peak in California, known for its iconic conical shape and past eruptions.
* Lassen Peak: The largest active volcano in the contiguous United States, with recent activity in the 20th century.
* Medicine Lake Volcano: A complex volcanic system with numerous cones and lava flows.
* Mount McLoughlin: A dormant volcano in southern Oregon, just across the border from California.
2. The Eastern Sierra Nevada: This region boasts a chain of volcanic peaks, including:
* Mono Craters: A group of volcanic domes and craters formed by explosive eruptions.
* Long Valley Caldera: A massive volcanic depression formed by a supervolcanic eruption in the past.
* Mammoth Mountain: A popular ski resort built on a Pleistocene-age volcano.
It's important to note that while some of these volcanoes are dormant, they are still considered active and have the potential to erupt in the future. The USGS closely monitors volcanic activity in California.
