The collision and joining of crustal fragments to a continent is called accretion.

Here's why:

* Accretion refers to the gradual growth of a larger body by the addition of smaller bodies. In geology, this specifically refers to the process where smaller crustal fragments, like island arcs or microcontinents, collide with and attach to the edge of a continent.

Let me know if you'd like to learn more about the process of accretion!