Question

The diagram below represents a series of rock layers found at a particular location. Each different type of shape shown in the layers represents a fossil of a different species.



Suppose each symbol is related to a particular species in the following ways:
A red triangle represents a species of marine crustacean.
A green circle represents a species of jawless fish.
A yellow square represents a species of tree moss.
A purple star represents a species of forest-dwelling insect.
The change shown in the diagram at the end of the Devonian geologic period could best be explained by
A.
the environment changing from a cold climate to a warm climate.
B.
the environment changing from ocean to dry land.
C.
the arrival of a new predator in the ecosystem.
D.
the melting of a glacier and development of freshwater lakes and rivers.

Answer 1

B

The lower layers contain marine fossils (crustaceans and jawless fish) while the upper layers contain terrestrial fossils (tree moss and forest insects). That shift indicates the area changed from an ocean environment to dry land (sea regression or uplift), not just a climate shift, a new predator, or formation of freshwater lakes.