4. Are there volcanoes currently in the Sierra Nevada mountains? Why or why no

The Sierra Nevada mountain range in California is not currently home to active volcanoes. The region is primarily composed of granitic rock, which is the result of ancient volcanic activity that occurred millions of years ago. The last significant volcanic activity in the Sierra Nevada occurred during the late Miocene to Pleistocene epochs, with the most recent eruptions happening around 10 million years ago. The lack of current volcanic activity in the Sierra Nevada is due to the tectonic setting of the region. The Sierra Nevada is located near the boundary of the North American tectonic plate, but it is not situated on a major plate boundary where active volcanism typically occurs, such as the Pacific Ring of Fire. Instead, the Sierra Nevada is characterized by uplift and erosion processes rather than ongoing volcanic activity. While there are some volcanic features in the broader region, such as the Mono-Inyo Craters and Lassen Volcanic National Park, these are not part of the Sierra Nevada range itself. Overall, the Sierra Nevada is considered a stable geological region with no active volcanoes at present.