by JM Schaefer et al., Nature, December8, 2016

Here we show that Greenland was deglaciated for extended periods during the Pleistocene epoch (from 2.6 million years ago to 11,700 years ago), based on new measurements of cosmic-ray-produced beryllium and aluminium isotopes (¹⁰Be and ²⁶Al) in a bedrock core from beneath an ice core near the GIS summit.