Slide 19 of 22
Notes:
Dalrymple regards radiometric dating techniques as the best indicator of an old Earth. He states (p. 398), "We know that certain long-lived radioactive nuclides found in rocks and minerals serve as natural clocks and that these clocks can be used in many circumstances to measure the ages of events in the history of the Earth and the other solid bodies in the Solar System".
"The majority of the 70 or so well-dated meteorites, however, have individual Rb-Sr, Sm-Nd, Pb-Pb, and Ar40/Ar39 ages of 4.4-4.6 Ga." Note: Ga = billions of years.
"The currently favored and only viable hypothesis for the formation of the Moon is that the Moon aggregated from the debris formed when a planetoid collided with the Earth. If this hypothesis is correct, then the minimum age for the Moon is also a minimum age for the Earth… three cumulates that are thought to have crystallized during formation of the lunar crust have Rb-Sr and Sm-Nd ages in the range of 4.42-4.51 Ga."
"Rocks exceeding 3.5 Ga in age are found on all the continents." Four well-studied areas of the Earth have produced ages (by more than one method) up to 3.9 Ga.
Perhaps the best evidence is that a table of the nuclides reveals that of the radioactive nuclides not currently being produced in the natural environment, only those with half-lives greater than about 80 Ma occur in nature. This implies "that a great length of time has passed since the elements were created and nuclides with half-lives less than about 80 Ma have simply decayed away." [Creationists have pointed out that the presence of this radiation would be detrimental to life and therefore would not be part of a mature creation.]
The "best value" of 4.54 Ga, was derived by Tera "using the congruency point of the four oldest conformable lead ores."
