A sediment core is removed from the floor of an inland sea. The sea has been in existence, off and on, throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilised in this core. The core is illustrated as a vertical column, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonised by life.
If arrows indicate locations in the column where fossils of a particular type (see key) first appear, then which core in the figure above has the most accurate arrangement of fossils?

Question

A sediment core is removed from the floor of an inland sea. The sea has been in existence, off and on, throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilised in this core. The core is illustrated as a vertical column, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonised by life. 
If arrows indicate locations in the column where fossils of a particular type (see key) first appear, then which core in the figure above has the most accurate arrangement of fossils?

Quizplus · Accepted Answer

Core A has the most accurate arrangement of fossils because it shows the correct order in which the terrestrial organisms first appeared, from the oldest at the bottom to the most recent at the top. Core B has some of the organisms appearing out of order, and Core C and D are missing some organisms or show them appearing too early or too late in the column.

A Sediment Core Is Removed from the Floor of an Inland