I already know what most of the "geochronical indicators" are. I want to know which ones they relied on in this case.
They never tell you in the popular press, they always leave that out.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V66-48C8KYS-1FD&_user=99318&_handle=V-WA-A-W-BW-MsSAYWW-UUA-U-AAAWEDEECA-AAAUCZUDCA-EDADEWDZV-BW-U&_fmt=summary&_coverDate=09%2F30%2F1991&_rdoc=26&_orig=browse&_srch=%23toc%235806%231991%23999449990%23418848!&_cdi=5806&view=c&_acct=C000007678&_version=1&_urlVersion=0&_userid=99318&md5=aedd70e4125104f8c9860f3f12b29090