Relative Dating
What is erosion?
Gradual wearing away of rock/rock formations due to environmental factors (usually water and wind)
What is the major difference between absolute dating and relative dating?
Absolute dating provides an exact (close to) age of a rock or fossil; relative dating can only tell us which part is older or younger.
List the four eras IN ORDER from most ancient to most recent.
Precambrian
Paleozoic
Mesozoic
Cenozoic
What are the two periods of the Cenozoic Era?
Paleogene and Neogene
What is included in the study of geology?
Rocks, rock formations, age of the earth
What causes sediment to form horizontal layers?
Gravity
What is the most common method of absolute dating?
Radioactive decay
Microscopic single-celled bacteria.
Which era was also called the age of reptiles?
Mesozoic Era
Fossils
What is an inclusion AND what do we know about the relative age of inclusions?
Inclusion is a small piece of rock inside of a larger rock. The inclusion is the oldest part of the rock and the surrounding rock layers are younger.
Explain what "half-life" means.
The time it takes for HALF of the unstable atoms to decay into stable atoms.
Which era covers about 85% of Earth's history?
Precambrian Era
When did human ancestors first appear in the fossil record?
4 million years ago
About how old is the earth?
4.5 billion years OR 4.6 billion years
Explain what the principle of superposition tells us about the relative age of rock layers.
The layers found on the bottom of a rock formation are the oldest; layers on top are the youngest.
What are two commonly used isotopes in the process of radioactive decay?
Carbon-14 and Uranium-238
What are the two major units of time that Earth's geologic history can be broken down into?
Eras and periods
Explain why the Cenozoic Era is also known as the Age of Mammals.
Mammals were the most dominant life form during this era - higher diversity and abundance of mammals than during any other era. NOT the first time mammals appeared.
About how long ago was Pangaea formed?
250 million years
True or false: All parts of a horizontal rock layer are the same age and composition.
ALSO explain which principle of relative dating supports/explains this.
True - principle of horizontality.
Explain what it means that an atom is considered to be "unstable."
Loses mass and matter over time. Stable atoms do not change over time. Unstable atoms change until they become stable.
What event ended the Precambrian Era AND describe what happened.
Cambrian Explosion - "explosion" of the diversity of life forms found on Earth.
During which era did birds first appear? AND
During which period did birds first appear?
Mesozoic Era
Jurassic Period
List at least TWO pieces of evidence that supports the Theory of Pangea.
-matching fossils on separated continents
-continent coastlines fit together like puzzle pieces
-matching rock layers on separated continents
-animals found on separated continents that could not have swam or flown over the ocean