These steep rock layers in a quarry near Salzgitter are unique in the world. Because no other formation shows the transition of the two Cretaceous ages Turon and Coniac 89.4 million years ago so completely and well preserved.
The history of the earth has left its traces everywhere on our planet – in the form of fossils, but also in the sequence of different deposits and rocks. They reflect the ups and downs of the sea level, the growth of large reefs or volcanic eruptions and phases of erosion. In order to be able to assign the different geological ages and their subsections, there are global reference points – places where these shift changes are particularly evident. They are known as the “Global Stratotype Section and Point” (GSSP) or “Golden Nail”.
One of these “golden nails” is now in a former limestone quarry near Salzgitter-Salder in Lower Saxony. Because there geologists have found what they have been looking for for more than 20 years worldwide: a rock formation that perfectly depicts the transition between the Turon and Coniac Cretaceous ages. This transition 89.4 million years ago marks the change from a tropical-warm section of the Upper Cretaceous, characterized by a high sea level, to a phase of slight cooling and sinking levels.
“The sequence of layers in Salzgitter-Salder was able to prevail over other candidates, for example in the USA, India, Madagascar, New Zealand and Poland, because here we have a perfect sequence of rock layers over 40 meters that represents a well-defined image of the events that took place in this geological time interval took place, ”says Ireneusz Walaszczyk from the University of Warsaw. In addition to the change in the ratio of carbon isotopes 12C and 13C, which is typical for the transition, the formation also shows the appearance of the Coniac key fossil Cremnoceramus deformis erectus.
Because of the good conservation of the key features and the length of the layer sequence that has been preserved, the International Commission for Stratigraphy (ICS) has now officially declared the exploration in the quarry near Salzgitter to be a “Global Stratotype Section and Point” (GSSP). One of the global reference points in the history of the earth is now in Lower Saxony.