Using Fossils for Geologic Dating Back in the Industrial Revolution – coal was in demand! Excavations of canals for coal and iron were done and these excavations exposed bedrock, which previously had been covered by vegetation.

Engineers learned to recognize distinctive layers of sedimentary rock and to identify the fossil assemblage A particular assemblage can be found only in a limited interval of layering

These observations have been repeated at millions of locations, and has been named the principle of fossil succession Once a fossil species disappears in a sequence of strata, it never reappears higher in the sequence

This provided the geologic underpinning for the theory of evolution!

Fossils are also used to determine the relative age of the beds! Index fossils (guide fossils): used by geologists to associate the strata with the specific time interval

Becoming a Fossil