The answer key prints on its own page, so you can keep it back. Prints in black and white on A4 or Letter.
TerraPrinter Classroom · Worksheet · Ages 11–16
Calderas and crater lakes
Name Class Date
A caldera is a huge bowl left when a volcano collapses. After a very big eruption, the chamber of magma under the volcano is partly empty, and the top of the volcano falls in. Use the models of Crater Lake and Ngorongoro to explore two calderas.
Open a link in a web browser to see the model in 3D, or use the printed model from your teacher.
Measure the width of Crater Lake on the print in mm. The whole model is 150 mm across for 15 km. How wide is the lake in km?
A crater at the top of a volcano is usually less than 1 km wide. Explain why a caldera can be so much bigger.
Crater Lake sits where a tall volcano, Mount Mazama, stood until it erupted and collapsed about 7,700 years ago. Follow the outer slopes upward and sketch what Mount Mazama might have looked like before.
Find the island near the west shore of Crater Lake. What do you think it is, and how did it form?
No rivers flow into Crater Lake. Where does its water come from? Why doesn't the lake overflow?
On the Ngorongoro model, the floor is about 600 m below the rim. The model is 150 mm across for 30 km, drawn 1.5× taller than true scale, so 1 mm of height is about 133 m. How many mm deep is the bowl on the print? Measure it to check.
Ngorongoro's floor is mostly grassland with a shallow lake and swamps, not a deep lake. Give one reason.
terraprinter.com/classroom/worksheet/calderas/
TerraPrinter Classroom, CC BY 4.0: free to copy and adapt with credit.
TerraPrinter Classroom · For the teacher
Answer key: Calderas and crater lakes
Learning goals
Explain how a caldera forms when a volcano collapses after a huge eruption.
Tell a caldera from a summit crater by its size.
Explain how water fills a caldera, and why some calderas hold deep lakes and others do not.
Answers
Measure the width of Crater Lake on the print in mm. The whole model is 150 mm across for 15 km. How wide is the lake in km?About 80–100 mm on the print, which is about 8–10 km. The real lake is about 8 by 10 km (5 by 6 miles).
A crater at the top of a volcano is usually less than 1 km wide. Explain why a caldera can be so much bigger.A caldera is not blasted out like a crater. A huge eruption empties much of the magma chamber below, and the whole top of the volcano collapses into the empty space.
Crater Lake sits where a tall volcano, Mount Mazama, stood until it erupted and collapsed about 7,700 years ago. Follow the outer slopes upward and sketch what Mount Mazama might have looked like before.The outer slopes continue upward into a tall cone above the middle of today's lake. Geologists think Mount Mazama was about 3,700 m (12,000 ft) high, more than 1,000 m above today's rim.
Find the island near the west shore of Crater Lake. What do you think it is, and how did it form?Wizard Island. It is a small cinder cone, a young volcano that grew from eruptions inside the caldera after the collapse.
No rivers flow into Crater Lake. Where does its water come from? Why doesn't the lake overflow?Rain and lots of snow fall straight into it and run down the inner walls. Water leaves by evaporation and by seeping out through the rocks, so the level stays about the same. It is the deepest lake in the USA, 594 m.
On the Ngorongoro model, the floor is about 600 m below the rim. The model is 150 mm across for 30 km, drawn 1.5× taller than true scale, so 1 mm of height is about 133 m. How many mm deep is the bowl on the print? Measure it to check.600 ÷ 133 ≈ 4.5 mm.
Ngorongoro's floor is mostly grassland with a shallow lake and swamps, not a deep lake. Give one reason.Less rain falls there than at Crater Lake and the hot sun evaporates water fast, so the water never builds up into a deep lake. (Water also drains away and sediment has filled the floor over 2–3 million years.)
Before the lesson
Print the models at 150 mm wide, 0.2 mm layers, 10–15% infill, no supports. Both use 1.5× vertical exaggeration. The lakes are cut into the terrain, so Crater Lake shows as a flat surface inside the rim even on a single-colour print; a blue filament change at the lake level makes it stand out. Measurements on the sheet assume the 150 mm size. Students' measured answers will vary a little with how they measure. Discussion questions and a hands-on activity for this topic: terraprinter.com/classroom/#calderas
