The second factor was an increase in the weathering of the Appalachian rocks between 462 and 454 million years ago, which is indicated by changes in strontium isotope ratios in Ordovician oceanic rocks (Geology, DOI: 10.1130 / g30152a.1). (newscientist.com)
The pair analyzed the ratio of strontium isotopes in rocks from Nevada and Europe that date to the Ordovician climate reversal. (scientificamerican.com)
Black pitch, carved histories: Radiocarbon dating, wood species identification and strontium isotope analysis of prehistoric wood carvings from Trinidad's (myintimcity.com)