M2 Subtopic 5

Question 1

As sediments accumulate, they form distinct layers, each representing a different period in Earth’s history; are like pages in a book, with each layer telling a different part of Earth’s story

Answer 1

Stratification

Question 2

are like pages in a book, with each layer telling a different part of Earth’s story

Answer 2

Stratified Rocks

Question 3

Two Dating Methods

Answer 3

Relative and Absolute Dating

Question 4

Establishes the sequence of events without determining their exact age. Used to understand the order in which layers and geological events occurred.

Answer 4

Relative Dating

Question 5

In an undisturbed sequence of rock layers, the oldest layers are at the bottom, and the youngest are at the top.
This principle helps geologists identify the relative ages of different layers.

Answer 5

Principle of Superposition

Question 6

Sedimentary layers are originally deposited in a horizontal position.
If layers are found tilted or folded, these changes occurred after deposition.

Answer 6

Principle of Original Horizontality

Question 7

A rock or fault that cuts across other layers is younger than the layers it disrupts.
This principle is crucial for understanding the sequence of events that have affected rock formations.

Answer 7

Principle of Cross-Cutting Relationships

Question 8

Fossils of organisms that lived during a specific, relatively short time frame.
Widely distributed and easily recognizable, making them ideal for correlating the age of rock layers across different regions.

Answer 8

Index Fossils

Question 9

provides a precise numerical age for rocks and fossils.
This method is essential for calibrating the geological time scale and understanding the timing of specific events in Earth’s history.

Answer 9

Absolute Dating

Question 10

measures the decay of radioactive isotopes within minerals to determine the exact age of rocks.
Widely used for dating igneous and metamorphic rocks and is key to determining the ages of ancient geological formations.

Answer 10

Radiometric Dating

Question 11

the time it takes for half of the radioactive isotopes in a sample to decay

Answer 11

Half life

Question 12

specific form of radiometric dating used to date organic materials, such as wood, bones, and shells.
Effective for dating materials up to about 50,000 years old.

Answer 12

Carbon Dating

Question 13

organizes Earth’s history into a series of time intervals.
These subdivisions are based on significant events such as mass extinctions, major climate shifts, and the emergence of new life forms.

Answer 13

Geologic Time Scale

Question 14

Subdivisions of Geologic Time

Answer 14

Eons, Eras, Periods, Epochs

Question 15

The largest time units, encompassing billions of years. (Precambrian and Phanerozoic)

Answer 15

Eons

Question 16

Subdivisions of eons, marked by significant changes in Earth’s biosphere (Paleozoic, Mesozoic, Cenozoic)

Answer 16

Eras

Question 17

Smaller time units within eras, often defined by the types of life that dominated (Jurassic, Devonian)

Answer 17

Periods

Question 18

The smallest divisions, representing specific changes in climate and life within periods (Holocene, Pleistocene)

Answer 18

Epochs

Question 19

Covers over 4 billion years of Earth’s history, including the formation of Earth and the emergence of early life.

Answer 19

Precambrian

Question 20

The current eon, starting around 541 million years ago, marked by abundant fossil evidence and the rise of complex life.

Answer 20

Phanerozoic

Question 21

Known as the “Age of Fishes,” it saw the development of complex life in the oceans and the colonization of land by plants and animals

Answer 21

Paleozoic Era

Question 22

The “Age of Reptiles,” dominated by dinosaurs, and the breakup of the supercontinent Pangaea

Answer 22

Mesozoic Era

Question 23

The “Age of Mammals,” characterized by the rise of mammals and, eventually, humans

Answer 23

Cenozoic Era

Question 24

Part of the Mesozoic Era, famous for the dominance of dinosaurs and the evolution of birds

Answer 24

Jurassic Period

Question 25

The current epoch, which began approximately 11,700 years ago, marked by the development of human civilizations.

Answer 25

Holocene Epoch

Question 26

also known as guide fossils, are the remains of organisms that were widespread geographically but lived during a relatively short and specific time period.
These fossils are crucial for identifying and correlating the ages of rock layers across different regions.

Answer 26

Marker Fossils

Question 27

Characteristics of an Effective Marker Fossil

Answer 27

Widespread Distribution
Short Time Range
Abundant Fossil Record

Question 28

The organism must have lived in various locations around the world, making its fossils common in many areas.

Answer 28

Widespread Distribution

Question 29

The species must have existed for a brief period, allowing for precise dating of the layers in which its fossils are found.

Answer 29

Short Time Range

Question 30

The organism should have left behind a substantial number of fossils, making it easier to find and identify in different rock layers

Answer 30

Abundant Fossil Record

Question 31

Extinct marine arthropods that lived during the Paleozoic Era, particularly useful as marker fossils.
Helps date rock layers from Cambrian to Permian Periods

Answer 31

Trilobite

Question 32

Marine mollusks that lived during the Mesozoic Era, particularly during the Jurassic and Cretaceous periods.
Their rapid evolution and wide distribution make them valuable for dating and correlating rock layers from these periods.
Defines Jurassic and Cretaceous periods on Geologic Time Scale

Answer 32

Ammonites