Base your answers to questions 51 through 54 on the cross section below and on your knowledge of earth
science. on the cross section, numbers 1 through 7 represent rock units in which overturning has not occurred.
line xy represents a fault and line wz represents the location of an unconformity

the three index fossils below are found within rock units 1, 2, and 3. since the rock units were deposited during different geologic time periods, each fossil is found in a different rock unit.