Scientists study these rocks and the fossils they contain to unravel the ancient past and prehistoric life of southwestern Illinois.
(Scientists; study; these rocks and the fossils) (they; contain; to unravel the ancient past and prehistoric life of southwestern Illinois) Context(they contain,List([45, 57))):(they; contain to unravel; the ancient past and prehistoric life of southwestern Illinois)
they contain,List([45, 57))
Scientists they they
study contain contain to unravel
these rocks and the fossils
to unravel the ancient past and prehistoric life of southwestern Illinois
the ancient past and prehistoric life of southwestern Illinois