A New “Golden Spike” Monument in Colorado Marks Geologic Time
Andrew Alden [source] | October 31, 2013
For something that is supposed to keep track of 4 billion years of history, the geologic time scale is quite a fuzzy and slippery yardstick. After two centuries of careful research and argumentation, the world’s geologists have only recently adopted a system to literally nail down the different time periods taught in geology school.
Last week that project took another slow step forward as a “golden spike” was officially driven into a precise spot on the ground near Pueblo, Colorado, a benchmark for the beginning of the Turonian Age.
The Turonian is, in the ICS’ geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma (million years ago). [Wikipedia]
The Western Interior Seaway then divided North America into eastern and western halves; Appalachia and Laramidia.
24 million years after the Turonian ended, a massive asteroid struck the Yucatan, spelling the end for the dinosaurs.
 Photo courtesy Brad Sageman
 Ichthyornis by S.V.Naugolnyh
 Cover to American Journal of Botany, 89(12), 2002, showing leaf and pinecone litter on a Turonian Coastal Plain forest floor with the oldest unequivocal fossil monocot
 Zuniceratops by cheungchungtat
 The Turonian Stratotype Section near Pueblo, Colorado. Photos courtesy Bob Kay
 J of Sedimentary Research [X]
 Chronostratigraphic chart