Chapter 11 Flashcards
How old is Earth?
4.54 billion years old
Relative Age Dating
What happened first, what happened next, and what happened most recently.
Uniformitarianism
Assumes the same physical processes that are occurring today have operated throughout geologic time.
Superposition
Sedimentary rocks are created in succession, with the oldest rocks at the bottom, and progressively younger rocks above.
Original Horizontality
If flat rocks are no longer
horizontal, some tectonic event
tilted the layers to the angle
they are now.
Cross-Cutting Relationships
Geologic features such as dikes and faults that cut across rock must be younger than the rock they cut.
Lateral Continuity
Rock layers are continuous until encountering an obstruction.
Faunal Succession
When they become extinct, fossil organisms disappear from the rock record everywhere at the same time and do not reappear in younger rocks (extinction is forever)
William Smith
Index fossil
Exists only for a brief interval of time; considered units of study in Biostratigraphy.
Correlation
The process of matching up the
ages of rocks found in different
places, i.e. finding rocks of
equivalent age.
Absolute Age Dating
Establish when an event took place in the past.
Radiometric Dating
Using the rate of decay for different unstable isotopes to pinpoint the ages of Earth materials.
Element
Material consisting entirely
of one kind of atom.
Atom
Smallest amount of an element
that can exist.
Atoms of an elements have the same atomic number but…
…can vary in the
number of neutrons.
