What forms at each kind of plate boundary
Grade 9 Science Worksheet - Building Confidence
Circle the best answer.
Station A moves east at 3 cm a year. Station B moves west at 2 cm a year. Station A lies west of a boundary and Station B lies east of it. What boundary lies between them, by Bo's reading?
- Convergent: the stations close in by 5 cm a year
- Divergent: the stations move apart by 5 cm a year
- Convergent: the stations close in by 1 cm a year
- Transform: the stations slide past each other by 5 cm a year
Read this first
Card (example data)
Sea-floor rock is youngest in the central valley and gets older on both sides. Plates on each side move away from the valley.
A sonar survey crosses a mid-ocean valley. What boundary and process explain the pattern, by Jun's reading?
- A convergent boundary, where old crust is recycled along the valley
- A hotspot, where a plume builds a ridge inside the plate
- A transform boundary, where plates slide past along the valley
- A divergent boundary, where new crust forms along the valley
When two continents meet head-on, neither subducts. Continental crust is light and buckles upward. India and Asia are both continental plates. Which statement about their meeting fits the card, by Luz's reading?
- India sinks under Asia, forming a deep trench and a volcanic arc along the range
- Asia sinks under India, forming a deep trench beside the new mountain range
- Neither plate sinks; the light crust buckles up into the Himalayas
- The plates part, and a rift valley forms between the two continents in the middle
Transform faults offset ridges, plates slide past each other there, and earthquakes are shallow. A map shows a ridge cut into offset pieces by cracks at right angles to it. What are the cracks, by Milo's reading?
- Transform faults, where plates slide past with shallow earthquakes
- New ridges, where the sliding plates make new crust between the offset pieces
- Hotspot tracks, where volcanoes line up inside a plate away from the ridge
- Trenches, where plates sink and crust is recycled along each offset piece
The vast majority of earthquakes and volcanoes occur near plate boundaries. Hotspots are long-lasting hot regions below plates. Hawaii formed more than 3,200 km from the nearest plate boundary. What explains its volcanoes, by Noah's reading?
- A transform fault that crosses the islands, where two plates slide past
- A nearby divergent boundary right under the islands, where two plates part
- A nearby convergent boundary right under the islands, where one plate sinks
- A hotspot: a long-lasting hot region below the plate
Card (USGS)
The presumed hotspot under Yellowstone is a hot region below the plate. The vast majority of volcanoes occur near plate boundaries.
Yellowstone lies far from any plate edge. What does USGS presume lies below it, by Pia's reading?
- A hotspot, a long-lasting hot region below the plate
- A mid-ocean ridge, where plates part and new crust forms below the park
- A transform fault, where two plates slide past each other under the park
- A subduction zone, where one plate sinks beneath the continent under the park
Card (USGS)
The vast majority of earthquakes and volcanoes occur near plate boundaries. Hawaii formed more than 3,200 km from the nearest boundary.
Which statement about where volcanoes occur fits the card, by Ren's reading?
- Most are near boundaries, and hotspots explain exceptions such as Hawaii
- Volcanoes occur near boundaries, and hotspots are boundaries too
- Volcanoes occur on boundaries without exception, and Hawaii is a boundary
- Volcanoes occur far from boundaries, and boundaries have few of them
Earthquake depths across a trench (example data)
Distance inland from trench Depth 0 km 10 km 50 km 60 km 100 km 110 km 150 km 160 km Tala reads the table. What pattern do the earthquake depths show?
- They get shallower farther inland, tracing a plate that rises as it goes
- They stay near 10 km at each distance, tracing a flat fault under the land
- They are deepest at the trench and shallow inland, tracing a plate rising
- They get deeper farther inland, tracing a plate sinking beneath
At subduction zones, earthquakes lie in a zone sloping down under the overriding plate and reaching several hundred km. A map shows shallow quakes at a trench and deep quakes 300 km inland. Which boundary fits, by Zee's reading?
- Convergent, where one plate sinks under another
- A hotspot, where a plume rises under a plate
- Transform, where plates slide past at the surface
- Divergent, where plates part and crust is made
At a ridge plates part and crust is made. At a trench one plate sinks, and quakes follow it down. Earthquakes at a ridge stay shallow, but at a trench they reach several hundred km. Which reason fits, by Esme's reading?
- At a ridge nothing sinks, but at a trench the plate carries quakes downward
- At both, plates sink, but trenches are older and so their quakes are deeper
- At a ridge the quakes are deeper, because the new crust there is thicker
- At a ridge a plate sinks, but at a trench the crust stays at the surface