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Relative dating principle

relative dating principle-80

The geologic timescale is a chronology (calendar) of events on Earth based on obtaining ages of past events.These ages have been derived from relative dating and absolute dating (radiometric dating) of rock layers and fossils.

This is similar to what geologists do to determine age.(a) Relative Dating This technique uses principles of stratigraphy (rock strata) and the study of fossils (palaeontology) to determine the relative ages of rocks and sediments. Field geologists' rely on a number of simple techniques for dating rocks and constructing geological successions. The Law of Strata Identified by Fossils is a little bit more complex.(relative geologic timescale) (b) Absolute Dating Following the discovery of radioactivity in 1895, radiometric dating techniques were developed to determine the absolute ages, i.e. In the succession of strata, each layer represents the geographical conditions that occurred over that area at the time the layer was deposited.At Thornton Force the junction is marked by a basal conglomerate. uniformitarianism is the phenomenon in which the processes that are operating at that moment were the same in the past, meaning a river that is flowing was also flowing in the past from the same direction.True xenoliths are definitely older than their host rocks but sometimes igneous rocks contain cognate inclusions or restite material.

S-type granites for example (granite with a sedimentary protolith) may contain such inclusions which are genetically related to its host rock.

As it is free swimming it could have travelled a considerable distance.

When found in rocks as far away as Australia you could reasonably expect those rocks to be the same age as those in Cliviger Valley!

The principle of inclusions states that inclusions found in other rocks (or formations) must be older than the rock that contain them. Geologists call it relative dating — we know which one is older but do not know how old they are.

This is actually pure logic and it can be applied not only in geology, but it is especially useful for geologists. Inclusions of foreign rocks that are found in igneous rocks are named xenoliths.

A third fact emerges from the study of stratigraphy - the UNCONFORMITY.