Vocab
The time needed for half of a radioactive substance to break down and undergo radioactive decay to form daughter isotopes.
What is Half-Life
What do radioactive isotopes start out as?
What is Parent Isotopes
Every time a substance goes through a half life, what happens?
What is half of the parent isotopes break down into daughter isotopes
This is a break in the geologic record. (when a rock layer is missing)
What is an unconformity
How old is Earth?
What is 4.6 Billion Years Old
A rock is dated using the Potassium-Argon method. If it was discovered that some of the Argon daughter isotope had been lost from the mineral crystals, the calculated age of the rock would be and WHY
A. too old
B too young
C. unaffected
Too young because if some of the daughter is lost then the percent of parent would be higher which means the half-life would be less.
The unstable/radioactive isotope is known as ____? And the stable isotope is known as ____?
What is parent isotope. What is daughter isotope.
What do isotopes become after breaking down?
What is Daughter Isotopes
What is the half-life of Carbon-14
What is 5,730 years
This states that youngest rock is found towards the top of rock layers, while oldest is found near the bottom.
What is the law of superposition
The weather conditions in an area over a long period of time, measured by temperature and precipitation.
What is climate
The breakdown of a radioactive isotope into a stable isotope is called _________.
What is Radioactive Decay
This type of radiometric dating is used to find the age of things like bones, wood, and shells (fossilized organisms).
What is Radiocarbon dating, using Crabon-14
80 atoms of a substance go through ONE half life. How many parent isotopes are left? Include the percentage of parent isotopes left too.
What is 40 parent isotopes and 50% parent isotopes remain.
Name 5 ways rock records can be disturbed.
What is:
Extrusion/Intrusion, Fault, Unconformity, Tilting, Folding
List the characteristics of a good index fossil.
What is:
1. Abundant /common
2. Spread over a large area
3. Easily distinguishable
4. Live for a relatively short geologic time period
Current geological processes can explain past geological processes.
What is uniformitarianism.
Explain how we can use Index Fossils to absolute date rock layers.
What is index fossils provide us with the accurate age of the rock layers they are found in. For example, if we find an index fossil we know is 200 million years old, we can age that rock layers at 200 million years old as well.
A substance has a half-life of 20 years. If 60 years pass, how many half-lives has the substance gone through?
What is 3 half-lives
The law that states when events such as an intrusion/extrusion or faults cut through other rocks or events, that they will be younger than any event they cut through
What is Law of Crosscutting Relationships
The principle of uniformitarianism states...
What is the current geological processes can be explained by past geological processes. The present is key to the past.
Determining the age of an object by comparing the number/percentages of parent isotopes to the number/percentages of daughter isotopes
What is Radiometric Dating
Scientists find a fossil. It is discovered that there is 12.5% of Carbon14 remaining in the fossil. How old is the fossil (half-life of C14 is 5730)
7190 years
A substance has a half-life of 15 years. You start with 48 atoms of this substance. After 45 years, how many parent isotopes will be left
What is 6 parent isotopes
Give the definition of Relative Age and how it is different from Absolute Age.
What is determining whether an object or event on younger or older than another object or event. It is different from absolute age because it does not give EXACT age, only a relative sequence of events.
what does the law of crosscutting state?
A fault or rock such as an intrusion is younger than the rock it is cutting through.