Simplify the following text for a Grade 9 native English-speaking person.
Original: Long undisturbed by tectonic activity , the peninsula is an extremely eroded , almost level low plain dominated by mighty meandering rivers and vast floodplains , with some very low hills rising to some 800m elevation in the McIlwraith Range on the eastern side around Coen .
Simplified: The peninsula is an extremely eroded , almost level , low plain with mighty meandering rivers and vast floodplains . There are some very low hills , about 800m above sea level in the McIlwraith Range on the eastern side around Coen .