Coniacian

The Coniacian is an important time period in Earth's history, part of what scientists call the geologic timescale. It is a smaller part of a much larger time called the Late Cretaceous Epoch, which is also known as the Upper Cretaceous Series.

This special time in Earth's past lasted from about 89.8 million years ago to 85.7 million years ago. Before the Coniacian was a time called the Turonian, and after it came another time called the Santonian. Studying these time periods helps scientists understand how our planet and its life have changed over millions of years.

Stratigraphic definitions

The Coniacian is named after the city of Cognac in the French region of Saintonge. It was first defined by a French geologist in 1857.

The Coniacian overlaps with a regional stage in Germany. In magnetic studies, it is part of a long period with normal polarity.

Sequence stratigraphy and geochemistry

After a high point in sea level during an earlier time, the Coniacian saw a slow drop in sea level. This change is part of a major pattern in Earth's history. There was also a temporary rise in sea level during the middle Coniacian.

Beginning in the middle Coniacian, a special condition in the water happened in the Atlantic Ocean, leading to the formation of certain types of rock. This condition lasted until a later time and was the longest of its kind during a certain period.

Subdivision

The Coniacian is often split into lower, middle, and upper parts. It includes certain areas defined by fossils in one region:

• zone of Paratexanites serratomarginatus
• zone of Gauthiericeras margae
• zone of Peroniceras tridorsatum

In another region, the Coniacian matches just one area defined by fossils: that of Forresteria petrocoriensis.