Once scientists have found dark-colored layers of rock from the geologic time they are studying, they start hunting for fossils.
(scientists; have found; dark-colored layers of rock) (they; are studying; T:the geologic time) (they; start; hunting for fossils; T:Once scientists have found dark-colored layers of rock from the geologic time) Context(they start,List([97, 107))):(they; start hunting; for fossils)
they start,List([97, 107))
scientists they they they
have found are studying start start hunting
dark-colored layers of rock
T:the geologic time
hunting for fossils T:Once scientists have found dark-colored layers of rock from the geologic time
for fossils