Lab-7

Geology Name:_______________________ Volcanoes Lab Report Please record your responses in a color other than black or red . Part 1: Locating and describing volcanoes 1. Using the Crater Lake topographic map , name three sites that you think formed due to volcanic activity. Crater Lake, Wizard Island, and Erta Ale. 2. Locate Wizard Island on your topographic map . How do you think Wizard Island formed? A large volcanic eruption that left a crater and sent volcanic material everywhere and left molten rock and ash to set everywhere around the crater. 3. Using your Geologic map, locate Wizard Island. What kind of rock is the island made of? I would guess andesite due to its relation to volcanic activity and the characteristics. 4. Using your Geologic map , locate Mariam Cone. What kind of rock is it made of? I would say a mixture of basalt and andesite, maybe even obsidian. 5. Which is older: Wizard Island, or Mariam Cone? How do you know? Wizard Island is older, you can tell due the the size of the crater and the massive amounts of layering Wizard Island has over Red Cone. 6. Using your Geologic map, locate Pumice Flat (southern edge of the map). Identify the mountain that erupted and deposited these rocks. (Hint: This formed the rock type labeled "cu-cp"). Cinder Cone. 7. List the locations in order from what formed earliest to what formed last. Crater lake, Wizard Island, and Red Cone. 8. Summarize the relationship between volcanic rocks, volcano types, hazards, and plate tectonic setting (plate boundary) by filling in the table below. Use reliable resources to find this information (lecture notes, textbook, or websites such as USGS Volcano Hazards Program or

Geology Name:_______________________ Volcanoes Lab Report Smithsonian Global Volcanism Program ). Volcano Type Plate Type/Tect onic Settings Magma chemistry (silica content) and characteri stics (viscosity & gas) Eruptive Style Rock Type Hazards Shield Divergent Low (all) Effusive Basalt Lava flow, small eruptions. Composit e/Stratov olcano Convergent High (all) Explosive Andesite Gases, eruptions, ash fall, pyroclastic flow. Cinder Cone Continental Moderate (all) Explosive Basalt/Ande site Ashfall, volcanic rock from eruptions Caldera Convergent High (all) Explosive Rhyolite/Tra chyte Huge eruptions, pyroclastic flow, ashfall Part 2: Estimating crater size 1. Choose one mare basin on the Moon, and create a careful sketch below, accurately showing the size and location of the basin you chose. Mare Nectaris

Geology Name:_______________________ Volcanoes Lab Report That is where volcanic activity or impacts from objects have happened. 7. "Mare" means "ocean". The maria were named that based on telescope observations of the Moon from Earth. Based on your observations, do you think these could be oceans hundreds of years ago? Yes, but not seas of water, but seas of lava and magma. Part 3: Volcanoes of the Afar Triangle Feature A. Erta Ale 1. What different colors can you distinguish on the ground in the Erta Ale volcanic field? What kinds of environments do these colors correspond to? (A few of the harder-to-find ones have been marked, but also discuss the more common colors.) Black, red, green, yellow, white/gray, brown, light blue. A toxic, very acidic and hot area. 2. What kind of human enterprise is going on at the placemark "Industrial activity"? Some geological resource is being harvested here -- what is it? I would assume a mining operation, maybe a gold quarry or quartz, some minerals that are valuable in Ethiopia. 3. Magma comes to the surface here along a system of faults. What seems to be the direction of the main fault underlying the Erta Ale volcanic field? (North- to-south? East-to-west? …) North-West to South-East. 4. What type of volcano is Erta Ale? Record your response in the table on your Virtual Field Trip Report in the Volcano type column. Shield Volcano. 5. The most recent lava deposits at this volcano are visible as dark places on the surface (e.g. placemark "Erta Ale, lowest point"). What geologic feature controls the shape of the lava flows and forces them to spread out northwest to southeast, instead of equally in all directions? The angle of the valley and the fault of the Afar Triangle.

Geology Name:_______________________ Volcanoes Lab Report 6. What is the lighter material on the east and west flanks of the volcano? (e.g. placemark "Erta Ale, light-colored material") Tephra and Ash. Feature B. Borele Ale 1. Follow the same procedure for Borele Ale as you did in questions 1-3 for Erta Ale to complete the row for Borele Ale on your Virtual Field Trip Report . Measure the highest elevation of Borele Ale at the top of the mountain ("Borele Ale, highest point"), and the lowest elevation and horizontal distance using the boundary to the northeast of the volcano where the lava flows from Borele Ale meet the darker underlying layers ("Borele Ale, lowest point"). 2. Borele Ale and Erta Ale are about the same height, but have very different slopes. Using your measurements, draw a profile of each of the two, label it, and calculate its cross-sectional area. Which volcano has a larger volume? Feature C. unnamed feature 1. You can pick any one of these small volcanoes to answer the measurement questions by following the same procedure as before, but choosing a volcano that stands alone would probably be the easiest to measure (e.g. "Location C, high point" and "Location C, low point"). Measure the horizontal distance from the highest point on the rim of the crater to the bottom of the cone. 2. What is the white stuff on the ground here? (e.g. "Location C, white stuff".) Hint: the climate here is very hot and arid so it probably is not snow, and if you zoom in on the edges of the white patches you can see it forms a crust in a way that ash usually does not... what else might it be? Part 4: Final Questions 1. Notice that the different types of volcanoes here are associated with different eruption styles and magma compositions. For each of the