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Researchers study the chemistry of magma to predict how it will erupt. The Valles Caldera and the surrounding mountains erupted differently due to their geo-chemistry. Some volcanic "brews" are high in silica and are more likely to result in a violent eruption like the caldera-forming eruptions that created the Toledo and Valles Calderas. The instantaneous degassing and the high silica content of the magma would produce ash falls and ash flows such as the super-heated pyroclastic flows recorded at Mt St Helens and Mt Pinatubo. Scientists examine magma's geo-chemistry and pay close attention to how the ash, that was once magma in a magma chamber, flows and falls to understand the volcanic events of the region. The Jemez mountains and valleys have beautiful examples of pumice deposits, large lava domes, spectacular ash-flow tuffs,"glass-like" obsidian flows, and some darker basaltic flows. In the resources and lessons that follow, you can learn about the chemistry of magma and learn to read the geologic landscape.
Video Clip from Valles Caldera: The Science
Learn how to use scientific data to understand the Earth's systems by interpreting the graphs.
In the Lab and Activities section you can find creative ways to introduce your students to the importance of gas and pressure in volcanic eruptions. A student lab sheet that includes solubility graphs to interpret is also under Labs and Activities. The original graph was prepared for "Rockin" by Nelia Dunbar and modified for this lab by Rhonda Spidell.
Nelia Dunbar has the best job on the planet. In fact, she is all over the planet studying volcanoes by looking at the geochemistry of magma. She has completed research in New Zealand, Alaska, New Mexico and every year she makes the long journey to Mt Erebus in Antarctica. Check out this link and learn more about Dr. Dunbar and her career as a geochemist.