In the Paleozoic Era, is the Carboniferous, or carbon-bearing, Period. It lasted from 360 million years ago to 286 million years ago, a span of 74 million years. Within this period, there are two other periods; the Mississippian and the Pennsylvanian. They were named to help scientists distinguish the different rock layers of the Carboniferous from each other. The Lower Carboniferous rock layers are from the Mississippian Period, and are mostly limestone. The Upper Carboniferous rock layers are from the Pennsylvanian Period, and there is more carbon in these layers. This is the stratigraphy of the Carboniferous Period.

The Carboniferous climate was warm and moist in the beginning, but then turned cool. There was much glaciation, caused by Gondwanaland’s southern shift. The areas around the equator remained warm and humid, while the poles went through a severe ice age. This ice age lasted for millions of years, during which Gondwanaland was coated with sheets of ice. The atmosphere during this time had higher oxygen levels than any other time in history. This was caused by the speedy growth of ancient trees, which sucked much of the carbon-dioxide from the air. There were insignificant, if any, changes with the seasons.

There was much tectonic activity during the carboniferous, as Pangaea forms. Many mountain ranges were formed in this period. In the late Carboniferous, a collision of Gondwanaland and Laurassia created the Appalachian Mountains of the eastern United States, and the Hercynian Mountains of the United Kingdom. A second collision of Siberia and Eastern Europe produced the Ural Mountains.

As the Earth’s surface shifts so dramatically, we are wondering – Where exactly was North America in all this? Where was Chapel Hill, and what would it have been like to live in this area? The first map below shows what the land masses looked like then, in relation to North America’s position now. The red dot is where Chapel Hill is now. The terrain was rocky and mountainous. The second map takes a different approach to these questions, and displays where the land masses we recognize today were during the Carboniferous Period.

Above:The red dot is Chapel Hill’s location in the Early Pennsylvanian Period. The faint lines behind the land masses are the country and state boundaries we recognize today. Below: The red dot is Chapel Hill’s location from this point of view.


During the Carboniferous, plant life was abundant and much of the Earth looked like a rain forest. Seedless plants, Lycopsids for example, are the main cause of the carbon that defines this period. Fern-like plants, such as Neuropteris, dominated the coal swamps, though these plants went extinct before the end of the Paleozoic. Lepidodendron sternbergii was one of the great scale trees. Unfortunately, these trees went extinct during the Late Carboniferous.

Left: Neuropteris

Right: Lepidodendron sternbergii


There were major steps in evolution that took place during the Carboniferous. An increase in terrestrial habitat led to the appearance of the amniote egg. The amniote egg allows the ancestors of mammals, birds, and reptiles to reproduce on land. The first reptiles appear, as well as the first winged insects, the dragonfly for instance. During the Mississippian, shallow, warm waters covered much of North America. Many of the animals living in these waters, especially the crinoids, contributed their shells to the forming of limestone. Cockroaches appeared, as well as many more species of tetrapods, four-legged vertebrates.

The end of the Carboniferous was not a mass extinction as it is in many other cases. Instead, the end of the Carboniferous is marked by climate changes due to glaciers covering the South Pole. Some species did go extinct because of the climate changes. These were mostly invertebrates in the seas. Trilobites, some crinoids, and horn corals are among those that were headed towards extinction at the beginning of the next period, the Permian.