Plate boundaries are named by how the plates move relative to each other. Towards each other is convergent, away from each other is divergent, and sliding past is transform.
This lesson opens plate movement and tectonic processes, part of physical geography.
What is the one-glance test?
Look at the arrow heads, not at the labels.
| Arrows | Movement | Boundary |
|---|---|---|
| Heads point towards each other | Plates collide | Convergent |
| Heads point away from each other | Plates separate | Divergent |
| Parallel, in opposite directions | Plates slide past | Transform |
Each type also leaves a clue in the diagram: a sinking plate or a pile-up for convergent, rising magma or a gap for divergent, and a straight fracture line for transform.
Worked example: three original diagrams
An original question shows three diagrams. Name the boundary in each and quote the clue.
- Diagram A: two arrows point away from a central line, and hot rock rises in the gap. The arrows separate, so this is divergent. The rising magma supports it.
- Diagram B: two arrows run side by side in opposite directions along a straight line, with no rising magma and no sinking plate. This is transform, where plates slide past each other.
- Diagram C: two arrows point towards each other, and one plate dips under the other. This is convergent, and the dipping plate shows subduction.
A full answer names the type, the arrow direction and one supporting clue.
The mistake: reading the labels, not the arrows
A common slip is to name the boundary from a landform label, such as “mountain, so convergent”. The working may be right by luck, but it fails when the diagram shows a trench or a ridge and the label is hidden.
| Approach | Risk |
|---|---|
| Name from the landform label | Labels may be removed or misleading |
| Name from arrow heads | Works on every diagram |
| Quote both | Strongest answer, with evidence |
A second slip is to confuse arrows pointing in the same direction with transform. Transform arrows run in opposite directions.
Check yourself
An original diagram has two arrows pointing towards each other. Neither plate dips below the other, and a wide band of folded rock forms between them. Name the boundary and give your evidence.
Answer
The boundary is convergent, because the arrow heads point towards each other.
The folded band between the plates is the supporting clue: when two plates of similar thickness collide, neither sinks easily, so the crust is pushed up and folded.
What to study next
Next, connect each boundary to the landform it builds in linking a plate process to an identified landform. Then try the tectonic practice set.
If you want a teacher to test you on new arrow diagrams, see online one-to-one Geography tuition.