Carboniferous period (kärbənĭf`ərəs), fifth period of the Paleozoic era Paleozoic era (pā'lēəzō`ĭk)
..... Click the link for more information. of geologic time (see Geologic Timescale Geologic Timescale
Era Period Epoch Approximate duration

(millions of years)

Approximate number of years ago

(millions of years)

..... Click the link for more information. , table), from 350 to 290 million years ago.

Historical Geology of the Period

The Carboniferous period was marked by vast, coal-forming swamps (see also bog bog, very old lake without inlet or outlet that becomes acid and is gradually overgrown with a characteristic vegetation (see swamp ). Peat moss, or sphagnum , grows around the edge of the open water of a bog ( peat is obtained from old bogs) and out on the surface.
..... Click the link for more information. ) and a succession of changes in the earth's surface that, continuing into the Permian period Permian period (pûr`mēən)
..... Click the link for more information. , ended the Paleozoic era. The Carboniferous is often split into two divisions, the Mississippian and the Pennsylvanian; in the United States the break in the geologic sequence is so sharp that each division is commonly considered an independent period.

The Lower Carboniferous Period

In the Lower Carboniferous, or Mississippian, period, the submersion—on several occasions—of the interior of North America under shallow seas resulted in the formation of limestone, shale, and sandstone. In the Appalachian region, especially in Pennsylvania, great deposits of sandstone and shale were laid down by the erosion products from the eastern coastal highlands. In the far west the Rocky Mt. region was covered by shallow seas that deposited the Madison and Redwall limestones of the Grand Canyon.

The Lower Carboniferous in Europe was a period of submergence and great volcanic activity. E of the Rhine, shales, sandstones, and conglomerates were deposited; and in Russia, the Coal Measures formed. The close of the Lower Carboniferous was marked by mountain building in New Brunswick, Nova Scotia, the S Appalachian region, the SW United States, and Europe.

The Upper Carboniferous Period

In the Upper Carboniferous, or Pennsylvanian, period, there was at least one great submergence. In the E United States great deltas of sediments, now represented by the Pottsville conglomerate, were formed during the early Pennsylvanian. In Kansas, Nebraska, Arkansas, and Texas, the Pennsylvanian beds are chiefly shale, sandstone, and coal; over the Cordilleran (Rocky Mountain) region, marine limestone, with little coal; on the Pacific coast from California to Alaska, limestone and shale. The sea level also oscillated during the period and caused the formation of great marshes with extensive vegetation that was later transformed into coal, with Pennsylvanian strata containing the largest U.S. coal deposits. The Pennsylvanian coal fields of North America include the anthracite field of E Pennsylvania; the Appalachian field, from Pennsylvania to Alabama; the Michigan field; the eastern interior field, in Indiana, Illinois, and Kentucky; the western interior and southwestern field, stretching from Iowa to Texas; the Rhode Island field; and the Acadian field of SE Canada.

In the Upper Carboniferous of Western Europe, the Millstone Grit (the equivalent to the Pottsville conglomerate) is followed by the Coal Measures, which include the Welsh, English, Belgian, Westphalian, and Saar Basin fields. In the Mediterranean region and parts of Asia, the Upper Carboniferous environment resembled that of W North America.

The Upper Carboniferous was a period of marked disturbances caused by collisions of crustal plates. Gondwanaland, the supercontinent containing the continents of Africa and S America, had formed; Euramerica, part of Europe and N America, had fused into a continent to the north; and Angara, today's Asia, was also to the north of Gondwanaland. In Europe the Paleozoic Alps were thrust up; in Asia, the Altai and the Tian Shan; in North America, the Arbuckle and Wichita mts. and the ancestral S Rockies. The Indian peninsula became an active site of deposition; in the Himalayan geosyncline and much of China, mountain building was dominant. Crustal movements in the Andean geosyncline of South America affected the pattern of sedimentation over much of the continent.

Evolution of Plant and Animal Life

The plant life of the Carboniferous period was extensive and luxuriant, especially during the Pennsylvanian. It included ferns and fernlike trees; giant horsetails, called calamites; club mosses, or lycopods, such as Lepidodendron and Sigillaria; seed ferns; and cordaites, or primitive conifers. Land animals included primitive amphibians, reptiles (which first appeared in the Upper Carboniferous), spiders, millipedes, land snails, scorpions, enormous dragonflies, and more than 800 kinds of cockroaches. The inland waters were inhabited by fishes, clams, and various crustaceans; the oceans, by mollusks, crinoids, sea urchins, and one-celled foraminifera.

Carboniferous Period

Interval of geologic time 359.2–299 million years ago, marked by great changes in world geography. All the landmasses drew closer together as a result of tectonic plate movements. The supercontinent Gondwana occupied much of the Southern Hemisphere. By the end of the period, present-day North America, Greenland, and northern Europe were also linked to Gondwana. Siberia and China (including Southeast Asia) remained individual continents located at high latitudes in the Northern Hemisphere. During this period, swamp forests became widespread, and enormous coal deposits formed. Plants made great advances in adapting to complex forest environments, and vertebrates underwent extensive evolution. Amphibians became widespread and diverse, and reptiles appeared for the first time and rapidly adapted to many habitats.