Define stratigraphic dating
It is based on a synchronization of the NGRIP, GRIP, and GISP2 ice-core records that allows the parallel analysis of all three records on a common time scale.
The boundaries of the GS and GI periods are defined based on a combination of stable-oxygen isotope ratios of the ice (δO, reflecting mainly local temperature) and calcium ion concentrations (reflecting mainly atmospheric dust loading) measured in the ice.
Dating methods in archaeology establish the time and sequence of events that created archaeological deposits and layers, called strata, within those deposits. Absolute dating relies on biological, chemical (radiometric), geological/electromagnetic, or historical investigation to obtain the date range of a deposit.
(Examples of each method, respectively, are dendrochronology, carbon-14, archaeomagnetism, and the known year a city was destroyed.) Relative dating is based on stratigraphy (the tendency of younger layers to lie over older layers) and comparison of artifacts from undated sites to sites where dates are established.
It is too early in the scientific process and maybe even too early in the Anthropocene to arrive at a robust conclusion.
I think the question of why is most interesting, and relates to the unprecedented capacities of human societies to alter the Earth system.
Ellis, Owen Gaffney: In your opinion, when and why do you think we entered the Anthropocene?
Erle Ellis: I am convinced that we don’t have the full range of evidence needed to answer these questions.
Using this revised scheme, we propose a consistent approach for discriminating and naming all the significant abrupt climatic events of the Last Glacial period that are represented in the Greenland ice records.
How would today's sediments appear to a geologist millions of years in the future examining outcrops of sedimentary rock that originated in our time?