Simplify the following text for a Grade 7 native English-speaking person.
Original: The oldest continental crustal rocks on Earth have ages in the range from about 3.7 to 4.28 billion years and have been found in the Narryer Gneiss Terrane in Western Australia , in the Acasta Gneiss in the Northwest Territories on the Canadian Shield , and on other cratonic regions such as those on the Fennoscandian Shield .
Simplified: The oldest continental crustal rocks on Earth are between 3.7 to 4.28 billion years old . These have been found in the Narryer Gneiss Terrane in Western Australia , in the Acasta Gneiss in the Northwest Territories on the Canadian Shield , and on the Fennoscandian Shield .