Relative dating of geological strata
Playfair later commented that, "the mind seemed to grow giddy by looking so far into the abyss of time." Mc Phee (1998) points out that Hutton removed humans from a specious place in time just as Copernicus had removed humans from a specious position in the universe (p. Hutton gives us three more laws to consider when seeking relative dates for rock layers, one of which, the law of inclusions was described earlier.states any feature that cuts across a rock or sediment must be younger than the rock or sediment through which it cuts.
Examples include fractures, faults, and igneous intrusions.
In 1788 John Playfair came to see Hutton’s Unconformity in Inchbonny.
The unconformity consists of many vertical tilted layers of grey shale overlaid by many layers of horizontal red sandstone.
Once Steno recognized that the fossils he was contemplating (sharks teeth and sea shells) were formed in the sediments of oceans he was able to work out the basic rules of stratigraphy.
Steno formalized the laws of superposition, original horizontality, original continuity and inclusions in his publication entitled states that any inclusion is older than the rock that contains it.
The fossils in the strata are used to determine relative dates, the simpler the fossil the older the fossil.Time factors of millions and billions of years is difficult even for adults to comprehend.However, "relative" dating or time can be an easy concept for students to learn.131) and by Georges Cuvier (1769-1832), a French anatomist, and Alexandre Brongniart (1770-1847), a French naturalist and geologist, during their work on the deposits of the Paris Basin.Brongniart was the first to use fossils to date rock strata., which states that geologic events are caused by natural processes, many of which are operating in our own time.