Why is the discovery of radioactive decay important in geology (two reasons)?
Telling the age of the earth
Same geological proceses that operate today operated years ago
What is radiometric dating? What is it based on? Why is it important?
Is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.It is the principal source of information about the absolute age of rocks and other geological features, including the age of the Earth itself, and can be used to date a wide range of natural and man-made material
What does “half-life” mean?
The time required for one-half of the atoms of a radioactive substance to decay.
What are the difficulties associated with dating the geologic time scale?
•Radioactive elements are usually found in trace concentrations–Requires precise measurements of concentration•Isotopes may move over time–Weathering, metamorphism or other alterations may disrupt the clock•Some rocks don’t contain easily dated minerals
How do geologists usually date sedimentary rocks?
In an undisturbed sequence of sedimentary strata, the youngest layer is at the top, and the oldest layer is at the bottom
What do earthquake, earthquake focus and epicenter mean?
Earthquakes are natural geologic phenomena caused by the sudden and rapid movement of a large volume of rocks. The focus is the zone within Earth where the initial displacement occurs. The epicenter is the surface location directly above the focus