In convergent plate boundaries, one plate subducts under one another due to different density.
Ocean trench- When subduction occurs, a plate would be subducted, and the inbetween of two plates would leave a deep trench due to the motion. One example is the Mariana Trench.
Folded mountain belts- When the plate converge,pressure would be put on the place causing the crust to arch up and be folded. One of example is the Himalayas belt,which occurs when the Indo-Australian Plate and Eurasian Plate collide.
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