Simplify the following text for a Grade 4 native English-speaking person.
Original: The island of Taiwan was formed approximately 4 to 5 million years ago from a geosyncline ( via plate tectonics ) , and is part of an island arc .
Simplified: The island of Formosa ( or Taiwan ) was formed about 4.5 million years ago from a Geosyncline . It is part of an island arc .