11. Anomalies in chromium isotopic ratios found within the K-T boundary layer strongly support the impact theory. 12. Comets and terrestrial water have similar isotopic ratios . 13. The isotopic ratio of 18 O to 16 O, usually in foram tests or ice cores. 14. Temperature, isotopic ratios , elemental ratios, mercury & CO2 concentrations are all data points under close examination. 15. The isotopic ratio is " the smoking gun " of the particles'deep-space, pre-solar system origins, he added. 16. It then goes on to define what water is using an isotopic ratio stated in a molar fraction. 17. The isotopic clock resets may result from thermal effects changing isotopic ratios , and changes to cosmic radiation exposure. 18. Therefore, precise analysis of Pb isotopic ratios can be used to study the circulation of the different oceans. 19. Oxygen isotopic ratios , which may be measured very precisely, yield a unique and distinct signature for each solar system body. 20. The D / H isotopic ratio is a primary constraint on the source of H 2 O of terrestrial planets.
