What forms at each kind of plate boundary
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
Card (USGS)
The vast majority of volcanoes occur near plate boundaries. Hawaii formed more than 3,200 km from the nearest boundary, over a hotspot.
A student tells Esme that every volcano sits on a plate boundary. Which reply fits the card?
- Not supported; Hawaii is more than 3,200 km from a boundary, and a hotspot feeds its volcanoes
- Supported; Hawaii is a divergent boundary in the middle of the Pacific, so the claim holds
- Supported; hotspots count as plate boundaries, so Hawaii sits on one in the Pacific plate
- Not supported; most volcanoes are far from boundaries, and Hawaii is a typical example of that
Card (USGS)
At a transform boundary such as the San Andreas, plates slide past each other. Crust is neither produced nor recycled there.
A student tells Kira that the San Andreas fault makes new crust as plates slide. Which reply fits the card?
- Not supported; the fault is a trench, where crust sinks
- Not supported; plates slide past, and no crust is made or recycled
- Supported; sliding plates press together and crust is recycled along the fault
- Supported; sliding plates pull apart and new crust forms along the fault
Card (example data)
Plate N lies north of the boundary and moves 3 cm a year east and 2 cm a year north. Plate S lies south of it and moves 3 cm a year west and does not move north or south.
A boundary runs east to west. Which description fits the motion, by Luz's reading?
- Mostly sliding past at 6 cm a year, with some opening at 2 cm a year
- Mostly closing at 2 cm a year, with some sliding at 6 cm a year
- Sliding past at 3 cm a year, with some opening at 2 cm a year
- Opening at 6 cm a year, with some sliding at 2 cm a year
Card (example data)
The slab moves 7 cm a year along its dip. Depth rate = speed × sin(dip). sin 60° is about 0.87.
A slab dips 60° and sinks along its dip at 7 cm a year. About how long to reach 600 km depth, by Milo's math? (1 km = 100,000 cm.)
- About 10 million years
- About 100 million years
- About 8.6 million years
- About 1 million years
Three groups of volcanoes (example data)
Group Distance from nearest boundary Quake depths below Group A 60 km to 300 km Group B 3,200 km to 20 km Group C 80 km to 20 km Which group is best explained by a hotspot, and why, by Pia's reading?
- Group A: its deep quakes below it show a hot region under the plate, so a plume is likely
- Group C: it lies near a boundary, which is where hotspots form, with shallow quakes below
- Group B: it lies 3,200 km from a boundary, with only shallow quakes below it
- Group A: it lies close to a boundary and has deep quakes below it, so a plume is likely
Quakes 200 km inland of four trenches (example data)
Zone Depth of quakes Zone 1 168 km Zone 2 200 km Zone 3 280 km Zone 4 346 km Which conclusion does the table support, by Ren's reading? (Dip = angle whose tangent is depth ÷ 200 km.)
- Slab dip varies from about 40° to 60°, so no single dip fits every zone
- The four zones share one dip of 45°, since depth rises with distance in each
- Dip falls from 60° to 40° from Zone 1 to Zone 4, as depth rises
- Zone 4 has the shallowest dip, since its quakes are the deepest
The East African Rift is a divergent boundary, where a continent is pulled apart and a valley forms. A student says quakes along a line across a continent show a new divergent boundary. What added evidence would strengthen that, by Tala's reading?
- More quakes on one date, with no change in station positions
- GPS stations on both sides moving apart, with a lengthening valley
- A chain of volcanoes far from the line, with no sign of motion
- Deep quakes along the line, as at a trench
Card (USGS)
Divergent boundaries make ridges and rifts. Convergent boundaries make trenches, volcanic arcs and mountains. Transform boundaries slide plates past. Hotspots lie inside plates.
Which summary links boundaries to features, by Zee's reading?
- Divergent: ridges and rifts. Convergent: trenches, arcs, mountains. Transform: new crust. Hotspots: volcanoes on boundaries
- Divergent: ridges and rifts. Convergent: sliding. Transform: trenches and arcs. Hotspots: volcanoes on boundaries
- Divergent: trenches and arcs. Convergent: ridges and rifts. Transform: sliding. Hotspots: volcanoes inside plates
- Divergent: ridges and rifts. Convergent: trenches, arcs, mountains. Transform: sliding. Hotspots: volcanoes inside plates
The Marianas are ocean–ocean convergence. The Andes are ocean–continent convergence. The Himalayas are continent–continent convergence. Which summary pairs each place with its plates and features, by Ari's reading?
- Marianas: mountains with no trench. Andes: trench and island arc. Himalayas: trench and volcanic range
- Marianas: trench and island arc. Andes: trench and volcanic range. Himalayas: mountains with no trench
- Marianas: trench and island arc. Andes: trench and volcanic range. Himalayas: a rift valley
- Marianas: trench and island arc. Andes: mountains with no trench. Himalayas: trench and volcanic range
Card (USGS)
At subduction zones, earthquakes lie in a zone sloping 40 to 60° down under the overriding plate and reaching several hundred km.
Which summary of earthquakes at subduction zones fits the cards, by Bo's reading?
- Quakes stay shallow along a slab dipping 40 to 60°, reaching just a few km
- Quakes deepen toward the sea along a slab dipping 40 to 60°, reaching several hundred km
- Quakes deepen inland along a slab dipping 4 to 6°, reaching several hundred km
- Quakes deepen inland along a slab dipping 40 to 60°, reaching several hundred km