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TerraPrinter Classroom · Worksheet · Ages 11–16
Coastlines and the sea floor
Name Class Date
These models show the sea floor as well as the land, so you can see what lies under the water. Use the models of Santorini in Greece and the Strait of Gibraltar.
Open a link in a web browser to see the model in 3D, or use the printed model from your teacher.
On Santorini, trace today's coastline with your finger. Where are the cliffs highest: on the inside of the ring of islands, or the outside?
How did the ring of islands form?
The caldera is up to about 400 m deep, and the cliffs rise up to about 300 m above the sea. How far is it from the top of the cliffs to the deepest part of the caldera floor?
Find the small islands in the middle of the caldera. What do you think they are?
The Santorini model is 150 mm across for 18 km and drawn 1.5× taller than true scale. How many metres of real height does 1 mm of print height show? Could you see a 1 m rise in sea level on the print?
On the Gibraltar model (150 mm = 40 km), find the narrowest part of the strait between Europe and Africa. Measure it and work out its real width.
Why does a narrow, shallow strait like Gibraltar matter for ocean water and for ships?
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TerraPrinter Classroom, CC BY 4.0: free to copy and adapt with credit.
TerraPrinter Classroom · For the teacher
Answer key: Coastlines and the sea floor
Learning goals
Read land and sea-floor relief on one model.
Explain how a volcanic caldera filled by the sea forms.
Reason about sea level, scale and why coastal risk maps need detailed data.
Answers
On Santorini, trace today's coastline with your finger. Where are the cliffs highest: on the inside of the ring of islands, or the outside?On the inside, facing the flooded caldera. The outer slopes run down gently to the sea.
How did the ring of islands form?Santorini is a volcano. Huge eruptions, most recently about 3,600 years ago, emptied the magma chamber below, and the middle of the volcano collapsed into a caldera. The sea flooded in, leaving a broken ring of islands.
The caldera is up to about 400 m deep, and the cliffs rise up to about 300 m above the sea. How far is it from the top of the cliffs to the deepest part of the caldera floor?About 700 m.
Find the small islands in the middle of the caldera. What do you think they are?Young volcanic islands (Nea Kameni and Palea Kameni), built up by eruptions inside the caldera after the collapse. The last eruption there was in 1950.
The Santorini model is 150 mm across for 18 km and drawn 1.5× taller than true scale. How many metres of real height does 1 mm of print height show? Could you see a 1 m rise in sea level on the print?18,000 m ÷ 150 mm = 120 m per mm across; ÷ 1.5 = 80 m per mm of height. A 1 m rise would be about 0.01 mm, far thinner than one printed layer (0.2 mm = 16 m), so no. Planning for sea-level rise needs much more detailed height data.
On the Gibraltar model (150 mm = 40 km), find the narrowest part of the strait between Europe and Africa. Measure it and work out its real width.About 14 km, which is about 52 mm on the print.
Why does a narrow, shallow strait like Gibraltar matter for ocean water and for ships?It is the only natural way between the Atlantic and the Mediterranean, so all the water swapped between them squeezes through it: Atlantic water flows in at the top and saltier Mediterranean water flows out along the bottom. All ships between the two seas must pass through the same narrow lane.
Before the lesson
Print the models at 150 mm wide, 0.2 mm layers, 10–15% infill, no supports. These use bathymetry mode, which prints the real sea floor instead of a flat sea. Sea-floor data is much coarser than land data, so underwater shapes look smoother; that works best for areas of 10 km and up. 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/#coastlines
