Results from the geologic material are necessarily spotty, owing to the difficulties involved in obtaining samples that were both suitable for assay and derived from horizons whose stratigraphic position is known unequivocally. Many samples assayed were taken from horizons whose stratigraphic position is subject to doubt.
Two general results have emerged from the assay of samples of primarily geologic significance: (1) The dates obtained fall roughly into the same order as the stratigraphic sequence of deposits from which the corresponding samples were collected. From this it is inferred that most of the dates are acceptable as to relative position. (2) The dates obtained are generally more recent than had been believed by many geologists. A result of this nature has been welcomed by some, who believe it is more consistent with the observed slight weathering and erosion of the latest drift sheets than are the older dates current hitherto.