Newly formed land consisting of an arc-shaped island chain is called a volcanic arc.

Here's why:

* Volcanic Activity: These islands are formed by volcanic activity, typically along subduction zones where one tectonic plate slides beneath another.

* Arc Shape: The volcanic activity creates a chain of islands, often curved in an arc shape.

* Examples: Some well-known volcanic arcs include the Aleutian Islands in Alaska, the Mariana Islands in the Pacific Ocean, and the Lesser Antilles in the Caribbean.

Let me know if you'd like to learn more about volcanic arcs!