Numerical ages for boundaries between time units on the geologic time scale primarily resulted from the study of ________,in conjunction with relative age data.
A) fossil content and spatial relationships among igneous rocks
B) fossil content and spatial relationships among sedimentary rocks
C) radiometric dating of igneous rocks
D) radiometric dating of sedimentary rocks

Question

Quizplus · Accepted Answer

Numerical ages for boundaries between time units on the geologic time scale primarily resulted from radiometric dating of igneous rocks, which provide absolute dates for the time when the rocks formed. This data was then used in conjunction with relative age data, such as the fossil content and spatial relationships among sedimentary rocks, to establish the boundaries between time units on the geologic time scale. Radiometric dating of sedimentary rocks is less common, as it is more difficult to obtain reliable dates due to complications such as resetting of the clock during burial and diagenesis.

Numerical Ages for Boundaries Between Time Units on the Geologic