They document twenty-two examples of false rubidium-strontium isochrons and propose that such characteristics are inherited from the molten material's source at great depth in the earth.
The straight line plot is again explained by geologic process, not by time-dependent nuclear decay within the rock.
The analytical equipment used to determine the abundances of isotopes is more accurate in determining ratios of isotopes than their absolute abundances.
In order to give an initial response, we might confine our attention to dating of lava flows, the most easily dated rocks, and limit our discussion to the Grand Canyon, which contains thoroughly studied lava flows profoundly relevant to the creation/evolution question.
Furthermore, we might begin by focusing our investigation to "wholerock" potassium-argon (K-Ar) and rubidium-strontium (Rb-Sr) techniques, the two most popular methods for dating rocks.
Fictitious Isochron Ages The isochron method assumes that the datable lava flow cooled from molten rock having different Rb/Sr ratios but having uniform mixing isotopically (all samples having the same Sr graph with the slope of the line having no identifiable time significance! Noble, "Age of the Cardenas Lavas, Grand Canyon, Arizona," Geological Society of America Bulletin, 87 (Aug.
Such two-component mixing diagrams produce what Faure calls "fictitious isochrons." Another geologic cause for these straight line plots is offered by Brooks, James, and Hart.
Hart, "Ancient Lithosphere: Its Role in Young Continental Volcanism," Science, 193 (17 Sept.
The Grand Canyon is a beautiful, natural monument to the immense power of nature.
Several lava flows even reached the river, forming lava dams.
Although no Indian legends attribute them to recent eruptions, one early geologist remarked about the extraordinary freshness of lava: "It looks as fresh as any coulee of Vesuvius ejected twenty or thirty years ago." indicate a line appearing to form a good isochron in Figure 2, the slope determining an "age" of 1500-million-years.
Popular Dating Methods Both the K-Ar and Rb-Sr methods make use of radioactive decay of a parent isotope to a stable daughter isotope. Leeman, "Late Cenozoic Alkali-Rich Basalt from the Western Grand Canyon Area, Utah and Arizona: Isotopic Composition of Strontium," Geological Society of America Bulletin, 85 (Nov. Six analyses of Uinkaret Plateau basalts (U-33, U-35, U-59, U-24, U-43, U-58) were used.
Potassium-40 (Rb has occurred since the rock cooled from the lava flow.
Hamblin, "Late Cenozoic Voicanism in the Western Grand Canyon" in W.