Travel back in time 300 million years to the Carboniferous Period to see the origins of the coal in Carbon County at the "Journey to the Past - the Carboniferous" at the Mauch Chunk Museum & Cultural Center on Saturday, Oct. 1.

The program at the Museum, 41 West Broadway in Jim Thorpe, includes a comprehensive display of fossils from 11:30 a.m. to 2:30 p.m., and a slide presentation lecture by geoscientist Matt Bielecki from 1 p.m. to 2:30 p.m. There is no charge for the program.

The Carboniferous Period, a period over 50 million years before the arrival of the dinosaurs, was the time when the great coal beds were formed. Carboniferous means "coal-bearing," and it was the time that many coal beds were laid down. In Pennsylvania, this process was widespread.

Although the Carboniferous Period is known as the Age of Plants, insects thrived in the swamp forests, and there are fossil records of early amphibians and reptiles.

The Carboniferous was a time of active mountain-building, as the shifting continental plates created the Appalachian Mountains.

Today, coal appears as a black rock that occurs as layers in the earth that can be mined continuously for many miles. Most of these coal layers found in Pennsylvania range from a few inches up to 12 feet in thickness.

Geologists describe coal as a black rock composed of thermally altered and highly compressed plant material that grew millions of years ago in swamps and then was buried under great thicknesses of sand and mud. It now occurs as extensive layers within the rocks beneath the earth's surface.

Coal is a rock composed mostly of the elements carbon, hydrogen, and oxygen, plus smaller amounts of other elements such as nitrogen, sulfur, phosphorus, and calcium, all combined in highly complex chemical compounds. These chemical compounds are of the type that take up energy when they are formed and give off energy when they break down and return to their original state. It is this energy that is released when coal is burned.

Carbon, hydrogen, and oxygen are the main constituents of the compounds making up living plants that hold energy derived from the sun. When a plant dies, it is exposed to bacterial action and decay in the atmosphere. The chemical processes by which the plant stored the various elements and the sun's energy are reversed, and these elements and the energy are released. Only if the dead plant material is protected from decay, as by natural burial by sediments, is this reversal stopped.

Thus, coal is a rock composed of the altered and compressed remains of plant material, which, by burial, escaped decomposition and which occurs as layers within the surface rocks of the earth.

During the Carboniferous period, Pennsylvania's environment was similar to the swamps of the Florida Everglades or the lower Mississippi River flood plane. That environment provided the great quantities of plant material that later became coal layers in Pennsylvania.

The trees and other plants that grew abundantly in and around the shallow swamp produced a great accumulation of fallen leaves, twigs, branches, and trunks. These settled to the bottom of the shallow swamp or formed thick floating mats upon which other plants lived and died, adding still more plant debris. The stagnant water of the swamp helped to preserve the dead plant material from decay.

As sediments build upon these layers, the pressure and heat begins the transformation to peat, lignite, subbituminous coal, bituminous coal, and, under the right conditions, anthracite.