For example, a geologist may examine a cutting where the rocks appear as shown in Figure 1.
(Creationists do not agree with these ages of millions of years because of the assumptions they are based on.) Because of his interest in the volcanic dyke, he collects a sample, being careful to select rock that looks fresh and unaltered.On his return, he sends his sample to the laboratory for dating, and after a few weeks receives the lab report.Let us imagine that the date reported by the lab was 150.7 ± 2.8 million years.Our geologist would be very happy with this result.Would he have concluded that the fossil date for the sediments was wrong? Would he have thought that the radiometric dating method was flawed? Instead of questioning the method, he would say that the radiometric date was not recording the time that the rock solidified.
He may suggest that the rock contained crystals (called xenocrysts) that formed long before the rock solidified and that these crystals gave an older date.In fact, he would have been equally happy with any date a bit less than 200 million years or a bit more than 30 million years.They would all have fitted nicely into the field relationships that he had observed and his interpretation of them.He may suggest that some other very old material had contaminated the lava as it passed through the earth.Or he may suggest that the result was due to a characteristic of the lava—that the dyke had inherited an old ‘age’. 200.4 ± 3.2 million years) implies that the calculated date of 200.4 million years is accurate to plus or minus 3.2 million years.It relates only to the accuracy of the measuring equipment in the laboratory.