(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.
Nicolas Steno, William Smith, Georges Cuvier, Alexandre Brongniart, and James Hutton developed the basic rules for the science of stratigraphy.Just as Sherlock Holmes used his power of observation to decipher the clues to a suspect's past actions, we will let the blemishes and behaviors of the rocks tell us their past story. ) Remember that relative dating involves determining "which came first" rather than "exactly when did this happen." The first step to untangling the geologic history of an area is often to figure out what happened first, second and third, etc.without knowing the absolute ages at which the rocks themselves formed.The question is, how can geologists decipher the available record?To use an analogy, the record we have is the equivalent of loose-leaf rock diaries, utterly lacking dates, scattered all over the earth, whose pages have been subjected to the ravages of erosion.