【单选题】In 1831 when Smith was finally recognized by the Geological Society of London as the 'father of English geology,' it was not only for his maps but also for something even more important. Ever since pe...
A.
the rocks from different strata closely resembled each other
B.
he was often unable to find fossils in the younger rock strata
C.
their similarity to each other made it difficult for him to distinguish one rock type from another
D.
the type of rock between two consistent strata was always the same