Complex sentence: Mammoth Spring is a very large first magnitude spring and is the largest spring in the state of Arkansas and the third largest spring within the Ozark Plateau region behind the Big Spring and Greer Spring.
Split into simpler sentences: Mammoth Spring is a very large first magnitude spring. It is the largest spring in the state of Arkansas and the third largest spring within the Ozark Plateau region behind the Big Spring and Greer Spring.