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TerraPrinter Classroom · Worksheet · Ages 10–15
Rivers: meanders, canyons and deltas
Name Class Date
Rivers shape the land in many ways. They wear rock away in some places and drop sand and mud in others. Use the models of Horseshoe Bend, the Goosenecks of the San Juan and the Mississippi Delta.
Open a link in a web browser to see the model in 3D, or use the printed model from your teacher.
Draw a river bend (a meander) from above. Mark: where the water flows fastest, where it flows slowest, where the bank is worn away, and where sand is dropped.
On Horseshoe Bend, trace the river with your finger. Which wall is steeper: the outside of the bend or the inside? Why?
At Horseshoe Bend, the river is about 300 m below the rim. The model is 150 mm across for 3 km at true scale, so 1 mm is 20 m. How deep should the canyon be on the print? Measure it to check.
At the Goosenecks, the San Juan River flows about 10 km (6 miles) while moving only about 2.4 km (1.5 miles) west. Divide the river length by the straight distance. What does the answer tell you?
These are entrenched meanders: the river winds like a lowland river, but it has cut deep into rock. Suggest how this happened.
Look at the Mississippi Delta. Why is it called a bird's-foot delta?
Why does a river drop its sand and mud and build a delta where it meets the sea?
Delta land is only a metre or two above sea level. Give two dangers for people who live there.
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TerraPrinter Classroom · For the teacher
Answer key: Rivers: meanders, canyons and deltas
Learning goals
Explain how a meander forms: erosion on the outside of a bend and deposition on the inside.
Recognise entrenched meanders, where a winding river has cut deep into rock.
Explain how a delta forms where a river slows down and drops its sediment.
Answers
Draw a river bend (a meander) from above. Mark: where the water flows fastest, where it flows slowest, where the bank is worn away, and where sand is dropped.Fastest water and erosion on the outside of the bend, which cuts a steep bank (river cliff). Slowest water on the inside of the bend, where sand and gravel are dropped to make a gently sloping bar (point bar).
On Horseshoe Bend, trace the river with your finger. Which wall is steeper: the outside of the bend or the inside? Why?The outside. The river flows fastest round the outside of the bend and wears that side away most, leaving a sheer cliff. The inside has slower water, so its slope is gentler.
At Horseshoe Bend, the river is about 300 m below the rim. The model is 150 mm across for 3 km at true scale, so 1 mm is 20 m. How deep should the canyon be on the print? Measure it to check.300 ÷ 20 = 15 mm.
At the Goosenecks, the San Juan River flows about 10 km (6 miles) while moving only about 2.4 km (1.5 miles) west. Divide the river length by the straight distance. What does the answer tell you?10 ÷ 2.4 ≈ 4. The river is about four times longer than the straight line: it is very winding. A river is usually called meandering when this number is above about 1.5.
These are entrenched meanders: the river winds like a lowland river, but it has cut deep into rock. Suggest how this happened.The river once wound across flatter, lower land. Then the land (the Colorado Plateau) was slowly lifted up, and the river cut downward into the rock as it rose, keeping its bends.
Look at the Mississippi Delta. Why is it called a bird's-foot delta?The main channels push far out into the Gulf of Mexico, each lined by long thin strips of land, so from above they look like the toes of a bird's foot.
Why does a river drop its sand and mud and build a delta where it meets the sea?When the river flows into the still sea it slows down. Slow water cannot carry as much sediment, so the sand and mud settle out and build new land.
Delta land is only a metre or two above sea level. Give two dangers for people who live there.Any two of: flooding from storms and hurricanes, river floods, the land slowly sinking, sea-level rise, and land being washed away.
Before the lesson
Print the models at 150 mm wide, 0.2 mm layers, 10–15% infill, no supports. Horseshoe Bend and the Goosenecks are at true scale (1×), so the canyon walls are as steep as the real ones. The delta is almost flat: what stands out is the pattern of land and water, with the river channels cut into the print. 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/#rivers
