LEARNING ADVENTURE – VOLCANOES
This earthcache requires the use of a magnifying glass (included in the cache container).
If you wish to use a dissecting microscope for a more detailed view, contact me so we can agree on a time for you to come inside.
EARTHCACHE REQUIREMENTS
Each cacher must send his/her own answers to log a find. … “Geocachers must complete the tasks before they log the EarthCache as found.” (4.3. EarthCache logging tasks)
NOTE: Answers via message -and- log signature picture are required to post a find for this cache.
MOUNT ST. HELENS
View Explosions at Mount Saint Helens | How the Earth Was Made (S2, E10) | Full Episode | History
1a. MESSAGE …. What were three indicators that volcanic activity was occurring within Mount St. Helens?
1b. MESSAGE …. Name two discoveries scientists learned from the eruption of Mount St. Helens? These are the reasons it is considered a landmark event for scientists.
2. MESSAGE …. Using the magnifying glass observe the ash deposited at a, b, c. Which one was found at 5 miles, 22 miles, and 250 miles?
Take a tiny pinch of the ash located in the bison tube.
3a. MESSAGE …. Describe the color and texture.
3b. MESSAGE …. Determine the approximate distance that ash traveled. Use your observations from #2 to determine the distance.
3c. LOG …. Take a pic of the ash in your palm. This pic is your log signature.
MOUNT PINATUBA
4. MESSAGE …. Given the same volume of magma, what would the eruption of Mt. Pinatubo have been like if it had a chemistry like the lavas of the Toano Range, Nevada?
5. MESSAGE …. Using the magnifying glass observe the texture of the three ash samples. Place them in order from closest to furthest from the caldera.
ISLAND ARC VOLCANOES
6. MESSAGE …. Using the Weight Percent Chart -and Lava Composition Diagram, name the rock type associated with each of the four island arc volcanic events.
Example … If SiO2 weighed 54% and K2O weighed 1%, the rock type would be Basaltic Andesite.
a. Mt. Pinatuba / b. Mt. St. Helen’s / c. Kilauea / d. Toana Range
7. MESSAGE …. Based on the lava compositional data, rank each of the four volcanoes in order of expected eruptive explosiveness (lowest to highest).
FIELD
8. MESSAGE …. There are no volcanoes to view in this area. Instead, standing at the parking coordinates, which of the four island arc volcanoes would you see/feel the effects from the eruption? Explain.
OPTIONAL – Please respect the time and effort involved in creating this earthcache by adding A and B to your log.
A. JOURNEY OF THE MIND … Science explains what we observe. Relate (in your own words) something you found interesting in the reading. This adds to your learning adventure and your log.
B. JOURNEY OF THE HEART … Art shares our personal experience of what we see. Share something special you found on site, and why it is special to you. This is a memorable addition to your log and will make other hearts smile.
Journeys of Heart and Mind …
Stories to Touch the Heart and Puzzles to Challenge the Mind / Rainbow Tree Story
VOLCANOES
Volcanoes are openings, or vents where magma, tephra (small rocks), and steam erupt onto the Earth’s surface. The eruption of the magma forms a large, usually circular volcanic depression called a caldera. When magma reaches the surface, it is called lava. Volcanic eruptions can last days, months, or even years. Volcanic ash is a mixture of rock, mineral, and glass particles expelled from a volcano during a volcanic eruption. The particles are very small—less than 2 millimeters in diameter.
One of the main factors that determine how explosive a volcanic eruption will be is the composition of the magma. If magma is thin and runny, gases can escape easily from it, so it is less explosive. Magmas with higher silica concentration are more viscous, and thus move slower than magmas with less silica. Where tectonic plates come together, volcanoes often have thicker, viscous magma with high gas content. This combination is explosive because the gases cannot easily boil out.
MOUNT ST. HELENS
“Mount St. Helens, located in southwestern Washington State, erupted on May 18, 1980 at 8:32 a.m. Pacific Daylight Time. Before the eruption, the elevation of the volcano had been 9,677 feet. Afterward, it was 8,363 feet, having lost 1,314 feet in elevation. The explosion blew out the northwest side of the mountain and pulverized about a third of the volcano, which turned into mud and ash. The ash cloud blackened the sky as it traveled eastward, leaving detectable amounts of ash over an area of 22,000 square miles. The ash cloud reached a height of about 80,000 feet in less than 15 minutes after the eruption. It spread across the U.S. in 3 days and circled the globe in 15 days. In all, 1.4 billion cubic yards of ash were thrown into the air by the eruption of Mount St. Helens.”
MOUNT PINATUBO
Although Mt. Pinatubo has been dormant for more than 400 years, radiocarbon dates on charcoal from tephra beds indicate major volcanic activity 400-600 2300-3000 and 4400-5100 years ago. Volcanic activity has been building and shaping the Mt. Pinatubo region for several million years.
The first significant indicator of renewed activity at Mt. Pinatubo, located in the Philippines, came on 4/2/91 when a series of small explosions created a line of craters and fumaroles near the summit. Activity continued to escalate until there was a massive eruption. The energy of the eruption was 15 times greater than the 1980 eruption of Mt. St. Helen’s, located in Washington state. With an estimated 3 million cubic yards of ash and gas ejected into the stratosphere, Mt. Pinatubo is the largest eruption of its kind this century. Within a month after the initial eruption, gas and ash clouds completely circled the globe.
ISLAND ARC VOLCANOES
These are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries.
VOCABULARY
Caldera – large depression formed when a volcano erupts and collapses
Fumaroles – an opening in or near a volcano, through which hot sulfurous gases emerge
Lava – magma that reaches the surface
Lithosphere – solid, outer part of Earth
Magma – extremely hot liquid and semi-liquid rock located under Earth’s surface
Stratosphere – a layer of Earth’s atmosphere … Going upwards is the troposphere, stratosphere, mesosphere.
Tectonic Plates – sections into which the lithosphere is cracked
Tephra – rock fragments and particles ejected by a volcanic eruption
INTERESTING …
Is water technically lava? … When the surface of a lake freezes, the water changes from a liquid to a solid. Rocks that solidify from melted material are igneous rocks, so lake ice can be classified as igneous. If you get technical, it also means that water could be classified as lava.
Why is ice a mineral but not water? … Water does not pass the test of being a solid so it is not considered a mineral although ice; which is solid, is classified as a mineral as long as it is naturally occurring.
AMAZING … The following sculpture was formed from the Mount St. Helen’s ash. A testament to beauty from devastation!
RESOURCES
About Volcanoes / Ward’s Mount Pinatubo Ash Study Kit / Ward’s Mt. St. Helens Ash Study Kit
https://www.youtube.com/watch?v=4HIc6nBzsVg&t=21s
https://www.youtube.com/watch?v=fArB5Jz2wos
https://www.youtube.com/watch?v=4L1N-FDrGLk
https://guides.lib.uw.edu/research/mount_st_helens … Mount St. Helens 1980 Eruption: A guide to the printed and archival sources about the Mount St. Helens eruption on May 18, 1980.
https://www.upi.com/Archives/1991/06/19/Pinatubo-ranks-with-Mount-St-Helens/4189677304000/
https://www.usgs.gov/media/images/comparison-materials-emitted-notable-volcanic-eruptions
https://opengeology.org/petrology/5-explosive-volcanic-eruptions/?print=print
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2003GC000655
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL007i011p00949
https://www.dnr.wa.gov/Publications/ger_ri24_mount_st_helens_ash.pdf
https://www.researchgate.net/figure/Bulk-ash-grain-size-distributions-of-the-submarine-Mt-Pinatubo-tephra-layer-at_fig4_225491094
https://mshnvm.org/teachers-corner/lesson-plans-and-worksheets/
https://volcano.oregonstate.edu/mount-saint-helens-living-laboratory-curriculum
https://answersingenesis.org/geology/four-lessons-mount-st-helens-eruption/