I was trained as a stratigrapher / micropaleontologist in Utrecht and finished my MSc in 1984. However, I soon ended up as an integrated stratigrapher with the intention to combine the various disciplines of stratigraphy, and beyond, to reconstruct Earth System history in increasing detail. I do this in particular through constructing high-resolution astronomical-tuned time scales with their unprecedented accuracy, precision and resolution. During my PhD I established such a time scale for the Mediterranean Pliocene in close collaboration with Jan-Willem Zachariasse, and Hans Zijderveld and Cor Langereis of the Paleomagnetic Laboratory Fort Hoofddijk (Photo 1).

As a postdoctoral “Akademie” fellow, I continued in Utrecht to work with Jan-Willem, Cor, Lucas Lourens and Wout Krijgsman on the elaboration and extension of this time scale into the Miocene (Photo 2). We also started to work on continental successions in the Mediterranean, initially in Greece, as part of the COMCOM-project (Photo 3) and later in Spain with Hayfaa Adul Aziz and Hemmo Abels as PhDs (Photo 4). The construction and application of the astronomical time scales proved of great importance among others for reconstructing 1) the history of the Messinian Salinity crisis, 2) astronomical-induced climate changes as recorded in marine and continental archives and 3) the intercalibration with radio-isotopic dating (with Paul Renne, Jan Wijbrans and Klaudia Kuiper).

I was secretary and chair of the Subcommission on Neogene Stratigraphy (SNS) of the International Commission on Stratigraphy (ICS) from 1998 till 2012. I contributed to the formal definition of many stage boundaries (GSSPs), which are now formally defined in astronomically tuned deep marine sections in the Mediterranean. I am further part of the Subcommission on Stratigraphic Nomenclature of the ICS.

As coordinator, I participated in the EU-Marie Curie - Initial Training Network (ITN) GTSnext, the European contribution to International Earthtime initiative. In this network, we brought for the first time leading experts in Europe on U/Pb, Ar/Ar and astronomical dating together with the aim to intercalibrate these independent numerical dating methods and to significantly improve the Geological Time Scale of the last 100 millions of years. The intercalibration of Ar/Ar and astronomical dating resulted in an astronomically calibrated age for the Fish Canyon sanidine, the most widely used standard in Ar/Ar dating. This age and the resultant astronomical age of 65.97 Ma for the Cretaceous/Paleogene (K/Pg) boundary are incorporated in GTS2012, although this - controversial - issue is not yet solved.

During the last decade, my research interest in the astronomical climate control on continental sedimentary environments switched from the Mediterranean to North America where, again with Hayfaa Abdul Aziz and Hemmo Abels, I focused in close collaboration with Phil Gingerich and Mary Kraus on the fluvial successions of the Eocene Willwood Formation in the Bighorn Basin (Photo 5). This study expanded to include the Fort Union Fm in Montana and the Hoseshoe Canyon Fm in Alberta, Canada, partly within the framework of GTSnext. We now continue to work in Montana (Photo 6) within the framework of the VIDI project of Klaudia Kuiper with Lars Noorbergen as PhD, who recently completed his thesis about the astronomical control on fluvial sedimentary sequences.

And, after almost one decade, I am working again on the Messinian Salinity Crisis with Maria Tulbure as PhD, this time within the framework of the EU-Marie Curie ITN Medgate. At this time it looks like that the astronomical theory of climate is very generally accepted in view of a postcard with astronomical target curves from Tremiti Island, Italy (Photo 7) and the opening of an Astronomical Polarity Time Scale hotel on Crete (Photo 8).

Finally, I switched to the Precambrian working with an international research team and PhD Margriet Lantink on astronomical climate forcing and Milankovitch cycles in Banded Iron Formations 2.5 billion years ago (Photos 11 and 12) when System Earth was operating in a fundamentally different way. Focus is also on reconstructing the early history of the Earth-Moon system by determining the distance between the two bodies.