Complex sentence: A terminal moraine was formed across the center of Long Island creating a drainage divide, with streams such as Spring Creek flowing south from the moraine (in what is now Highland Park at modern Jamaica Avenue) towards Jamaica Bay.
Split into simpler sentences: A terminal moraine was formed across the center of Long Island. The moraine created a drainage divide, with streams such as Spring Creek flowing south from the moraine (in what is now Highland Park at modern Jamaica Avenue) towards Jamaica Bay.