Coniacian

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

The Coniacian lasted from about 89.8 million years ago to 85.7 million years ago. Before the Coniacian, there was a time called the Turonian. After the Coniacian came another time called the Santonian. Learning about these times helps scientists understand how Earth 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.

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.