Ammonite Biozones and the Biostratigraphic Column
It was the English engineer William Smith (1769-1839), who pioneered the idea that different strata located in different places could be correlated using the fossils that were contained therein. Although, his astonishing feat of compiling the world’s first geological map did not receive all the recognition it deserved, after all, it was only later in his life that his achievements gained prominence in scientific circles, William Smith is regarded by many as the “father of geology”.
As he examined different layers of rock he perceived that any succession of fossils could represent particular periods of geological time. Furthermore, the age of widely separated strata could be compared and correlated using the fossils that they contained. These fossils helped to indicate the relative age of various rock formations. Thus, Smith helped to lay the foundations for the science of biostratigraphy. Ammonites and other invertebrate fossils are extremely important in the relative dating process.
Different Fossils of Ammonites Associated with Different Layers of Rock – Building a Biostratigraphical Column
Picture Credit: Everything Dinosaur
The above photograph was taken by an Everything Dinosaur team member on a recent visit to the Naturmuseum Senckenberg (Frankfurt, Germany), it demonstrates that different types of ammonite fossils are associated with different layers of rocks in a sequence of deposition. The stratigraphic column can therefore be divided into zones (biozones), that are characterised by one or more particular type of fossil. The sequence of these biozones in the correct order, creates a biostratigraphical column.
Ammonites are ideal zone fossil candidates. These cephalopods were ubiquitous in Mesozoic marine deposits, their shells formed abundant fossils and ammonites evolved rapidly into many distinctive types (species). We congratulate the Museum for such a beautifully created and instructive display.