Relative Dating Laws
A sedimentary rock layer is found beneath three others. According to the Law of Superposition, this layer is most likely…
What is older than the layers above it?
A sample has 25% of its original radioactive material remaining. How many half-lives have passed?
What is two half-lives?
Most organisms never fossilize because they are destroyed by…
What is decay, scavengers, weathering, or erosion?
This is the layer where nuclear fusion actually occurs.
What is the Core?
A star that is hot and very bright would be located in which general area of the H-R diagram?
What is upper left?
A fault cuts through Layers M, N, and O. What must be true about the fault?
Answer: What is the fault is younger than the layers it cuts through?
A fossil contains 12.5% of its parent isotope. If the half-life is 50 years, how old is it?
What is 150 years?
A fossil is found worldwide but only existed for 2 million years. Why is this valuable to geologists?
What is it makes a strong index fossil for correlating rock layers?
Energy moves outward through electromagnetic radiation in this layer.
What is the Radiative Zone?
A cool but very bright star is most likely a…
What is a red giant?
Rock Layer B is found above Rock Layer D in an undisturbed sequence of sedimentary rocks. Which layer is older, and what principle explains this?
What is Layer D is older, according to the Law of Superposition?
A substance starts with 400g. After one half-life, how much remains?
What is 200 grams?
Which two characteristics make the BEST index fossil?
What is widespread and lived for a short time?
Hot plasma rises and cool plasma sinks in this layer.
What is the Convection Zone?
A hot but dim star is most likely a…
What is a white dwarf?
An igneous intrusion contains fragments of sandstone inside it. Which is older — the sandstone or the intrusion?
Answer: What is the sandstone is older (Law of Inclusions)?
A radioactive isotope has a half-life of 10 hours. How much of a 160g sample remains after 30 hours?
What is 20 grams?
Why wouldn’t a species that lived for 200 million years make a good index fossil?
What is it existed too long to narrow down a rock layer’s age?
This is the visible “surface” of the Sun that gives off light.
What is the Photosphere?
Which star would have the shortest lifespan: a blue giant or a red dwarf? Why?
What is a blue giant, because massive stars burn fuel faster?
A rock layer is tilted at an angle but sits below flat, horizontal layers. What likely happened first?
Answer: What is the tilting event occurred before the horizontal layers were deposited? (Earthquake)
A rock sample contains 6.25% of its original parent isotope. If the half-life of the isotope is 20 million years, how old is the rock?
What is 80 million years?
(6.25% → 4 half-lives → 20 × 4 = 80 million years)
If the same index fossil is found in rock layers in Illinois and Australia, what can scientists conclude?
What is those rock layers are the same age?
What process powers the Sun and other main sequence stars?
What is nuclear fusion (hydrogen into helium)?
Put these in order for a massive star:
Main Sequence, Supernova, Red Supergiant, Black Hole
Answer: What is Main Sequence → Red Supergiant → Supernova → Black Hole?