Rings To help find out, the team sliced thin cross-sections of the willow twigs. The thickest twig was less than a fifth of an inch in diameter, yet it bore more than 20 annual rings. That growth rate is even slower than that of modern Salix arctica, indicating the mammoth's climate was even more austere than that of northern Greenland, where S. arctica lives today. The cross-sections were even clearer as to season of death: When the mammoth ate the willow, the first spring vessels of the outermost rings were just forming—a clear sign that he had died in early spring.
