Relative dating geology
These techniques are more complex and advanced regarding technology as compared to the techniques in practice in relative dating.The absolute dating is also sometimes referred to as the relative numerical dating as it comes with the exact age of the object.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 8.6).Most commonly, the ancient factors of the rocks or objects are examined using the method called stratigraphy.In other words, we can say that the age in relative dating is ascertained by witnessing the layers of deposition or the rocks.In radiometric dating, the radioactive minerals within the rocks are used to know about the age of the object or the sites.
For example, the principle of superposition states that sedimentary layers are deposited in sequence, and, unless the entire sequence has been turned over by tectonic processes or disrupted by faulting, the layers at the bottom are older than those at the top.
(Hammerhead for scale) [SE]Figure 8.6b Rip-up clasts of shale embedded in Gabriola Formation sandstone, Gabriola Island, B. The pieces of shale were eroded as the sandstone was deposited, so the shale is older than the sandstone.
[SE] The principle of cross-cutting relationships states that any geological feature that cuts across, or disrupts another feature must be younger than the feature that is disrupted.
To evaluate the exact age, both the chemical and physical properties of the object are looked keenly.
The main techniques used in absolute dating are carbon dating, annual cycle method, trapped electron method, and the atomic clocks.