A Brief Overview of the Carboniferous Period for Middle School Science Classes

Dec 15, 2024

4 min read

Earth history is a fascinating topic! It is also a massive topic! The reading passage below will teach you all about the Carboniferous Period. If you want to learn more (and why wouldn't you?!), you can check out my Earth History page. I also have all of my passages available at Teachers Pay Teachers. They come with so many extras to get your students thinking about the content! I also recommend scrolling to the bottom of the page to check out my digital picture book on the Carboniferous Period!

There is a thick layer of coal deep underground throughout North America, Europe, and Asia.

This coal was formed from large numbers of tropical plants living millions of years ago. The

plants died but were not decomposed. Over time, layers of these plants built up. The heat and

pressure of these layers formed coal. In 1822, William Conybeare and William Phillips named

the period of time represented by the coal the Carboniferous period. Carboniferous means

related to coal.

The Carboniferous period is divided into two major subdivisions. The Mississippian subperiod

lasted from 359 to 318 million years ago. The rocks of the Mississippian subperiod are mostly

made up of the limestone that formed in the shallow seas of the time. The Pennsylvanian

subperiod lasted from 318 to 299 million years ago. The Pennsylvanian subperiod is made up of

large coal deposits.

During the Carboniferous period, the continent of Laurussia, which is sometimes called Eurasia,

combined with the continent of Laurentia to form Laurasia. North America, northern Europe,

and Asia were a part of Laurasia. The continent of Gondwana included South America, Africa,

India, Australia, Antarctica, and southern Europe.

Early in the Carboniferous period, Laurasia sat along the equator, and Gondwana was near the South Pole, but the continents continued to move toward each other throughout the period.

Along the equator, the climate was warm and moist. Lowland swamps were full of trees and

ferns. Fossils of these trees don’t show growth rings, which means there were no seasons, so the

trees grew all year. Some of the trees grew to one hundred feet tall.

The climate on Gondwana was much colder because it was close to the South Pole. Two giant

ice sheets covered the southern part of the continent. This explains why coal deposits were

found in North America, Europe, and Asia but not Africa, Australia, or Antarctica. The coal was

formed from tropical plants. There were no tropical plants in southern Gondwana.

In the oceans, life continued to evolve. Armored fish, such as the placoderms of the Devonian

period, went extinct. Graptolites went extinct. Trilobites would be extinct by the Permian period.

However, bryozoans, brachiopods, and cephalopods continued to thrive in the shallow seas.

Sharks and fish were at the top of the ocean food chain.

On land, tetrapods, four-legged vertebrates, continued to evolve. Some amphibians developed

scaly skin. They began laying amniote eggs. These eggs had a thick membrane that kept water

inside the egg but allowed oxygen and carbon dioxide to pass through it. These adaptations

meant the animals didn’t have to live in water anymore. The scaly skin and amniote eggs mark

the evolution from amphibians to amniotes. Amniotes are the ancestors of reptiles, dinosaurs,

and mammals.

Insects also changed during the Carboniferous period. The trees and ferns of the period were

removing carbon dioxide from the air and pumping massive amounts of oxygen back into the

air. Nearly 35 percent of the atmosphere was oxygen during the Carboniferous period. Today, oxygen makes up about 20 percent of our atmosphere. Scientists believe the large amount of oxygen available in the atmosphere led to giant insects. For example, centipedes were six feet long, scorpions were three feet long, and dragonflies were as big as seagulls.

Insects also developed the ability to fly during the Carboniferous period. Dragonflies and

mayflies were common. Scientists aren’t sure how insects developed wings and the ability to fly,

but they have a few hypotheses. One hypothesis is that insects had small flaps on either side of

their bodies that acted like a parachute when they jumped from high places. Over time, these

flaps grew larger and evolved into wings. Another hypothesis is that the insects had gills. At

first, these gills were used to breathe underwater but eventually became used to help the insect

move. Over time, the gills grew longer and became wings.

The Carboniferous period ended with the formation of the supercontinent Pangaea. All of the

land on Earth was locked in one giant island surrounded by an enormous ocean.

Carboniferous Period Picture Book

Looking for another way to learn about the Carboniferous Period? Check out this picture book version. The pages are a part of my Earth History bundle on Teachers Pay Teachers.