Continent-continent convergence
Topic: Continental Drift, Sea-floor Spreading and Plate Tectonics · NCERT: Class 11, Ch 4 "Distribution of Oceans and Continents"
Meaning
Continent-continent convergence is the collision of two plates that both carry continents at their front edges. Continental crust is light, so neither plate sinks easily into the mantle. Instead, the crust crumples, folds and thickens. This builds very high fold mountains. The ocean floor that once lay between the two continents is squeezed up, so marine rocks and fossils end up high in the mountains.
Example
The Himalayas formed when the Indian plate hit the Eurasian plate about 40-50 million years ago, after the Tethys Sea closed. This is the northern boundary of the Indian plate. India still pushes in at about 5 cm a year, and the Himalayas rise about 5 mm a year. The Indus-Tsangpo Suture Zone in Ladakh marks the join between the two plates. The Alps formed in the same way from Africa-Europe convergence.
Don't confuse with
- Ocean-continent convergence: there, heavy ocean crust sinks under the continent, which makes a trench and volcanoes (as in the Andes). In continent-continent convergence, neither plate sinks easily and there are few volcanoes.
Related concepts
- Convergent boundary
- Subduction zone
- Ocean-continent convergence
- Ocean-ocean convergence
- Island arc
- Fold mountain
- Wadati-Benioff zone