Geologic History of Earth Flashcards

Questions and Answers

What is the geologic time scale?

A timeline marking global temperature changes

A measurement used to chart the ages of fossils

The duration of a single geological event

The measurement to describe the timing and relationship of the events that have occurred throughout Earth's history (correct)

What are fossils?

Preserved remains of plants or animals found in rocks.

What is an index fossil?

A fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found.

How old is the Earth?

4.6 billion years. Signup and view all the answers

What does the Law of Superposition state?

In any sequence of rock or sediment layers, the youngest sediments or rocks are at the top of the sequence and the oldest are at the bottom. Signup and view all the answers

What is an eon?

The largest division of geologic time. Signup and view all the answers

What is the Precambrian?

Name for the time in Earth's early history that accounts for 88 percent of Earth's time, but only cellular organisms lived. Signup and view all the answers

What is the Paleozoic Era?

The part of geologic time from 570-245 million years ago when invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees were dominant. Signup and view all the answers

What is the Mesozoic Era known for?

Middle life (245-144 million years ago); rise of mammals and dinosaurs; the rise of birds; extinction of dinosaurs, rise of flowering plants. Signup and view all the answers

What marks the beginning of the Cenozoic Era?

Begun about 66 million years ago, known as the 'Age of Mammals'. Signup and view all the answers

What is absolute dating?

A technique used to determine the actual age of a fossil. Signup and view all the answers

What is relative dating?

Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock. Signup and view all the answers

What is the fossil record?

The mineralized remains of organisms and the rock layers in which they are found, showing when and where long-dead organisms lived and how their bodies were structured. Signup and view all the answers

What are rock strata?

The sedimentary layers of rock in Earth. Signup and view all the answers

Study Notes

Geologic Time Scale

A framework used to describe Earth's history in terms of timing and relationships of geological events.
Divided into eons, eras, periods, and epochs to help organize significant changes in Earth's formation and life.

Fossils

Preserved remains or impressions of plants and animals found in sedimentary rocks.
Provides crucial evidence of past life forms and their environments.

Index Fossil

Fossils that are used to identify and date the rock layers in which they are found.
Typically from organisms that existed during a specific time period, facilitating relative dating of geological strata.

Age of the Earth

Approximately 4.6 billion years old, indicating the duration of Earth's existence.

Law of Superposition

Geological principle stating that in undisturbed rock layers, the oldest layers are at the bottom, and the youngest are at the top.
Essential for understanding the chronological sequence of geological events.

Eon

The largest subdivision of the geologic time scale, encompassing significant periods in Earth's history.

Precambrian Era

Accounts for about 88% of Earth's history, characterized predominantly by the presence of unicellular organisms.
Represents a vast time before multicellular life evolved.

Paleozoic Era

Spanning from 570 to 245 million years ago, this era saw the dominance of invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees.
Marked significant evolutionary advancements in life forms.

Mesozoic Era

Known as the "Age of Reptiles," lasting from 245 to 144 million years ago.
Featured the rise of mammals and dinosaurs, the emergence of birds, and significant plant diversity, including flowering plants.
Culminated in the extinction event that wiped out the dinosaurs.

Cenozoic Era

Began around 66 million years ago, referred to as the "Age of Mammals."
Characterized by the diversification of mammals, birds, and flowering plants following the Mesozoic extinction.

Absolute Dating

A scientific method used to determine the precise age of a fossil or rock layer, providing numerical dates.

Relative Dating

A technique to estimate the age of a fossil based on its position relative to other fossils and rock layers.
Lacks precise date but helps to determine the sequence of geological events.

Fossil Record

A historical timeline formed by mineralized remains of organisms alongside their respective rock layers.
Illuminates the evolution of life forms, their distribution, and structure over geological time.

Rock Strata

Layers of sedimentary rock that are deposited over time, preserving the history of geological events.
Each stratum provides insights into the environmental conditions of the Earth's past.

Description

Explore the key concepts of Earth's geologic history through this flashcard quiz. Learn about important terminology such as the geologic time scale, fossils, and index fossils. Perfect for students studying Earth sciences or geology.