Common global stratigraphic markers are palaeo-events that occur worldwide synchronously, and can allow wiggle-matching between ice cores and other palaeo archives (e.g., marine sediment cores).
For the ice matrix, these global stratigraphic markers can include spikes in volcanic ash (each volcanic eruption has a unique chemical signature), or volcanic sulfate spikes.
Would other isotopes with longer half-lives be more accurate? Ice cores can be dated using counting of annual layers in their uppermost layers. Other ways of dating ice cores include geochemisty, wiggle matching of ice core records to insolation time series (Lemieux-Dudon et al.
2010), layers of volcanic ash (tephra) (Vinther et al., 2006), electrical conductivity, and using numerical flow models to understand age-depth relationships (Mulvaney et al., 2012), combined with firn densification modeling to estimate the delta-age (Lemieux-Dudon et al. Usually multiple methods are used to improve accuracy.
As the ice must be melted for analysis, the sample is usually destroyed during analysis. Consistent dating for Antarctic and Greenland ice cores.
which compared the spacing between frost ring events (physical scarring of living growth rings by prolonged sub-zero temperatures) in the bristlecone pine tree ring chronology, and spacing between prominent acids in a suite of ice cores from both Greenland and Antarctica.
The American National Ice Core Laboratory provides some information on how they store and keep ice cores. A synchronized dating of three Greenland ice cores throughout the Holocene.When ice cores are analysed, they may be cut or sectioned, with half the sample remaining as an archive. Recent Antarctic Peninsula warming relative to Holocene climate and ice-shelf history.