The principle of inclusions states that any rock fragments that are included in rock must be older than the rock in which they are included. For example, a xenolith in an igneous rock or a clast in sedimentary rock must be older than the rock that includes it Figure 8. A 50 cm wide light-grey felsic intrusive igneous dyke extending from the lower left to the middle right — offset in several places Using the principle of cross-cutting relationships outlined above, determine the relative ages of these three rock types.
The Proterozoic rocks of the Grand Canyon Group have been tilted and then eroded to a flat surface relative dating in rock to deposition of the younger Paleozoic rocks. The difference in time between the youngest of the Proterozoic rocks and the oldest of the Paleozoic rocks is close to million years. Tilting and erosion of the older rocks took place during this time, and if there was any deposition going on in this area, the evidence of it is now gone.
The flat-lying rocks at the top are Paleozoic to Ma.
Relative Dating Methods The principle of inclusions states that any rock fragments that are included in rock must be older than the rock in which they are. Steno's principles are used by geologists to determine the age of fossils and rocks in a process called relative dating. • Relative dating is a.