Here's why:

* Earth's crust is broken into pieces: The Earth's outer layer, the crust, isn't one solid piece. It's broken into large, moving sections called tectonic plates.

* They move and interact: These plates are constantly moving and interacting with each other. Their movements cause earthquakes, volcanic eruptions, and the formation of mountains and ocean trenches.

* Major plates: Some of the major tectonic plates include the North American Plate, the South American Plate, the Eurasian Plate, the African Plate, the Indo-Australian Plate, the Pacific Plate, and the Antarctic Plate.

So, while a "large segment of the crust" is technically correct, the specific term for it is tectonic plate.