Vocab
The age of one rock layer or fossil compared to another is...
relative age
The Law of Superposition states that...
in an undisturbed sequence of rock layers, the oldest layers are at the bottom, and the youngest layers are on top, because newer material is always deposited over older material
What happens to mantle material when it gets heated by the core?
HINT: temperature increases when it gets heated
It gets less dense and rises.
When magma cools, it forms which kind of rock?
Igneous
What makes a fossil a good index fossil?
HINT: index fossil characteristics
it must be distinctive, widespread, abundant, and have lived for a relatively short time
These fossils are easily recognizable, abundant, and widely distributed...
index fossils
In a column of rock with 4 layers, fossils in the lowest layer include trilobites, the next layer up contain marine organisms, the next layer on top of that contains dinosaur fossils, the top layer contains no fossils. Which fossils are the youngest?
trilobites, marine organisms, or dinosaur
dinosaur fossils are the youngest because they're closest to the top
What happens to mantle material as it gets closer to the crust and cools down?
It becomes denser and sinks.
This type of rock forms under intense heat and pressure...
metamorphic
What are two main ways to date fossils?
relative dating, and absolute (radiometric) dating
*bonus info:
radiometric dating is the most accurate way to determine a fossil's age
The "exact" age of a rock layer or fossil determined by radiometric dating...
absolute age
In a column of rock with 4 layers, fossils in the lowest layer include trilobites, the next layer up contain marine organisms, the next layer on top of that contains dinosaur fossils, the top layer contains no fossils. Which fossils are younger than trilobites, but older dinosaurs?
marine organisms because they fall between the trilobite fossils and the dinosaur fossils
True or False: Convection currents transfer heat away from the core towards the crust.
True
This type of rock is formed from small pieces of other rocks/sand through cementing & compacting...
sedimentary
What does the pH scale measure?
it tells us how acidic or alkaline a substance is
*bonus info
a value of 7 on the pH scale is considered "neutral"
The processes that continue to shape Earth today are the same processes that have shaped Earth since its formation...
uniformitarianism
In a column of rock with 4 layers, fossils in the lowest layer include trilobites, the next layer up contain marine organisms, the next layer on top of that contains dinosaur fossils, the top layer contains no fossils. What can we conclude about the fact that the top layer doesn't have fossils?
a mass extinction event likely occurred
What causes the cooler, denser material to sink back down?
HINT: why does it sink
Denser material is heavier, and gravity pulls it towards the core
Hot, molten rock that reaches Earth's surface is called...
lava
How do index fossils help correlate rock layers?
If the same index fossil is found in rock layers at different locations, geologists know those layers formed at roughly the same time.
Stacked up layers of sedimentary rocks, they form when sediments are washed into lakes and seas, then settle on the bottom....
rock strata
According to the Law of Superposition, a fossil found in the third layer from the bottom of an undisturbed rock sequence is likely _______________ than a fossil found in the fourth layer (the one directly above it).
older
In the Earth’s mantle, convection currents are responsible for...
plate movement
This type of "rock" is hot, molten material beneath Earth's surface...
HINT: molten refers to thick liquid
magma
What evidence do we have that some mountains were once under water?
HINT: the evidence can be found in rock layers
we find marine fossils on high mountain peaks
*bonus info:
"marine" refers to oceans or seas