Images Dated 3rd June 2005

FG-EA-736

FG-ea-736
GEOLOGY: K-T boundary - K-T boundary Sussex locality, Wyoming, USA.
The ruler and brush rest on the top of the K-T boundary layer. Below it is a mudstone deposit of the Lance Formation (Cretaceous). Above it is a coal bed of the Tullock Member of the Fort Union Formation (Tertiary). The K-T boundary layer is the gray to white kaolinitic claystone, less than 2 cm thick. On top of it is a darker, laminated layer a few millimeters thick, containing sand grains, many of them showing multiple sets of parallel fractures ("shocked quartz") under the microscope. Iridium can be detected in the claystone layer and in the carbonaceous layer immediately above it.
Francois Gohier

© Francois Gohier / ardea.com