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.
Principles of Stratigraphy Stratigraphy is the study of strata (sedimentary layers) in the Earth's crust.
Geologist in the 1800s worked out 7 basic principles of stratigraphy that allowed them, and now us, to work out the relative ages of rocks.
Click Question 1 (3 points): Find the list of hypothetical geologic examples and click on "fault." We are asked to determine the correct sequence of geologic events shown by the cross-section.
In order to do this, we need to apply the principles of relative dating which we have learned.
This is not an attempt at a comprehensive work of jurisprudence. The author is certainly no authority on the mechanic’s lien law in all fifty states.
Archbishop James Ussher of Armagh, Ireland, 1654, added up generations from the Old Testament and determined that Earth formed on October 23, 4004 BCE.
Between the years of 17, James Hutton and William Smith advanced the concept of relative dating.
Hutton, a Scottish geologist, first proposed formally the fundamental principle used to classify rocks according to their relative ages.
He concluded, after studying rocks at many outcrops, that each layer represented a specific interval of geologic time.
Further, he proposed that wherever un-contorted layers were exposed, the bottom layer was deposited first and was, therefore, the oldest layer exposed; each succeeding layer, up to the topmost one, was progressively younger.