Simplify the following text for a Grade 9 native English-speaking person.
Original: He followed Jim Jim Creek down from the Arnhem Land escarpment , then went down the South Alligator before crossing to the East Alligator and proceeding north .
Simplified: He followed Jim Jim Creek down from the Arnhem Land escarpment , then went down the South Alligator before crossing to the East Alligator and going north .