What is the principle that Earth's history can be explained by current geologic processes?
uniformitarianism
What is the law of superposition?
The law states that an undeformed sedimentary rock layer is older than the layers above it and younger than the layers below it
What is the difference between absolute age and relative age?
Absolute age is the numeric age of an object, relative age is the age of an object in relation to the ages of other objects
What are index fossils?
An index fossil is a fossile that is used to established the age of rock layers because it is distinct, abundant, and widespread and existed for only a short span of geologic time
In what type of rock are most fossils found
sedimentary rock
How was the geological column created?
scientists determined the relative ages of sedimentary rocks a round the world and combined the data to the data to form the column
What are the divisions of geological time?
era, period, epoch, ages
What does precambrian time include?
Hadean eon, Archean eon, the proterozoic eon. Includes the time from the formation of Earth unil 542 million years ago
For what is a geologic period named?
Each period is characterized by specific fossils and is usually named for the location in which the fossils were first discovered
Why is the gravity experienced on the moon's surface so much less than the gravity experienced on Earth?
Because the moon has much less mass than the Earth
Why doesn't the moon have an atmosphere?
Because the gravity is too weak to hold gasses
The planet with the most complex set of rings is?
Saturn
About how many starts are visible from earth without a telescope?
6,000
What is a small, hot, extremely dense core left after a star collapse called?
white dwarf
What type of galaxy is the Milky Way?
spiral
How does the sun produce energy?
nuclear fusion
What is the inner cone shaped area of an eclipses shadow called?
