Relative Age
What does relative age tell us about rocks?
Answer: It tells us if a rock is older or younger compared to another rock.
What does absolute age refer to?
Answer: It refers to the actual age of a rock or fossil in years.
What is an index fossil?
Answer: A fossil of an organism that was widespread but only lived for a short time.
What is relative dating?
Answer: The process of determining the order of past events without determining their absolute age.
What is the Precambrian Era?
Answer: The earliest part of Earth's history, covering about 88% of its age, before the Cambrian period.
How do scientists use layers of rock to determine relative age?
Answer: They study the order of rock layers, where the oldest layers are at the bottom and the youngest are at the top.
Which method is commonly used to determine absolute age?
Answer: Radiometric dating, which uses the decay of radioactive isotopes.
Why are index fossils useful in dating rocks?
Answer: They help correlate the ages of rock layers across different locations.
What is the Law of Original Horizontality?
Answer: It states that layers of sediment are originally deposited horizontally under the action of gravity.
What types of organisms lived during the Precambrian Era?
Answer: Mostly simple, single-celled organisms like bacteria and algae.
What is the principle of superposition?
Answer: In undisturbed rock layers, the oldest rocks are at the bottom and the youngest are at the top.
What is carbon dating used for?
Answer: To determine the age of organic materials up to about 50,000 years old.
Name one example of an index fossil.
Answer: Trilobites or ammonites.
How can faults affect relative dating?
Answer: A fault can cut through rock layers, indicating that it occurred after the layers were formed.
How long did the Precambrian Era last?
Answer: It lasted from the formation of Earth about 4.6 billion years ago until about 541 million years ago.
What is an example of a relative dating technique?
Answer: Fossil correlation, where fossils in different locations are compared to determine relative ages.
What is the difference between relative age and absolute age?
Answer: Relative age compares ages of rocks, while absolute age gives a specific numerical age.
How do scientists determine if a fossil is an index fossil?
Answer: They check if it is found in many places and if it existed for a short period.
What role do fossils play in relative dating?
Answer: Fossils help identify the relative ages of rock layers based on the types of organisms present.
What is one significant event that occurred during the Precambrian Era?
Answer: The formation of the first continents and the appearance of photosynthetic organisms.
Why is the study of relative age important in geology?
Answer: It helps scientists understand the history of Earth and the sequence of events over time.
How does uranium-lead dating work?
Answer: It measures the ratio of uranium to lead isotopes in a rock to determine its age.
What criteria must a fossil meet to be considered an index fossil?
Answer: It must be geographically widespread, abundant, and limited to a short time span in geologic history.
How does the concept of faunal succession relate to relative dating?
Answer: It states that fossil organisms succeed one another in a definite and recognizable order, allowing for age dating.
Why is the Precambrian Era often referred to as "the age of bacteria"?
Answer: Bacteria were the dominant life forms and existed for a significant portion of this era.