Two Stalagmites Found in Chinese Cave Are a 'Holy Grail' for Accurate Radiocarbon Dating

An unbroken record of atmospheric carbon-12 and carbon-14 was found near Nanjing, China, equipping scientists with a more accurate standard for use in radiocarbon calibration.

from gizmodo http://www.gizmodo.co.uk/2018/12/two-stalagmites-found-in-chinese-cave-are-a-holy-grail-for-accurate-radiocarbon-dating/