The Earth's outermost physical layer divided into tectonic plates is called the lithosphere.

Here's a breakdown:

* Lithosphere: This is the rigid, outermost layer of Earth, consisting of the crust and the uppermost part of the mantle. It's broken into large pieces called tectonic plates.

* Tectonic Plates: These plates are constantly moving, interacting with each other, and causing various geological phenomena like earthquakes, volcanoes, and mountain formation.

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