What is sea floor spreading?
Sea Floor Spreading happens when two plates break apart. The ocean floor extends because of this movement.
What are some of the major land forms that are created from plate movement?
Mountains, the 7 continents, volcanoes, islands, trenches, and other land forms were created due to the movement of these plates.

How were the Mariana Islands formed?
The Mariana Islands were formed by the underwater volcanoes. Most of these volcanoes stopped erupting and finally grew vegetation and served as a home for creatures.

What evidence exists today that the plates are still moving and that the islands are ancient volcanoes?
Earthquakes. Earthquakes are the reasons why we can know that the plates are moving.

What is an atoll?
a bunch of small island-like land form or bunch of piled sand cays that usually form a circular formation.

Why are atolls mainly found on the Pacific?
Well atolls are made up of reefs and sand cays. Pacific ocean is a best place for that things like these types of land forms.