Deep Time Flashcards
How are isotopes of the same elements the same?
Same number of protons and electrons
How are isotopes of the same elements different?
Different number of neutrons
What are radioisotopes?
Isotopes that give off radiation
Define Half Life
The time required for half of the atoms of a sample to decay into another stable isotope (nothing can change it)
How many half life does it usually take most radioisotopes to disappear?
20
No radioisotope is less than…?
1.0 X 10 (to the 6th)
Index fossil
A fossil that is useful for dating and correlating the strata in which it is found
Whats an Isotope?
An element of slightly different form
The Law of Superposition
The older layers of rock are on the bottom, the younger are at the top
Relative dating
This looks at lower levels of rock and the fossils they contain. It places them in a sequential sequence, and it’s used to estimate the time an organism lived.
Absolute dating
Using radioactive decay to determine the exact age of a rock, fossil, or event (looks at radio isotopes, how much it had then, has now
How are relative dating and absolute dating used?
Relative dating: when your trying to figure out which rock is older
Absolute dating: when your trying to find the exact date of the rock
How do you use evidence from absolute/radio metric dating to determine the age of the earth?
Using the oldest earth rocks and meteors, we can calculate the another of several isotopes with long half lives
Give three pieces of evidence that show the earths continents shift
- fossils that are the same but in different locations
- mountains/rocks that once fit together
- rock/coal that needs other climate to develope
How would you use characteristics to understand how closely related different species are
The more similar a species appears can relate to how long ago they diverged
