Klaerle’s "Coalcache" (Alabama)

Each coalcache geocoin is handmade from pulverized coal and resin. Supply is limited. The geocoin without a state abbreviation was made with coal mined in Southwest Virginia, PA from coal mined in Pennsylvania, WV from coal mined in West Virginia, AL from coal mined in Alabama and VA from coal mined in Virginia.

Coal is the preserved remains of land plants, including roots, bark, and wood. In the Appalachian coal basin, five major plant groups contributed to the formation of coal. These are lycopods, ferns, seed ferns, calamites, and cordaites. Appalachian coal was formed from vast deposits of peat derived from plant remains that accumulated in tropical and subtropical swamps during the Pennsylvania period of the Palcozoic era from 323 to 290 million years ago. A number of natural physical changes were involved as the peat accumulated, was buried, and underwent a process called coalification that gradually turned it into a solid, highly combustible fuel.

     A prime requirement for the transformation was a subtropical or tropical climate. As shifting tectonic plates rearranged Earth's continents during the late Paleozoic, the continent of Laurentia, consisting of what is now North America and Greenland, was located astride the the equator. Thus what is now eastern North America experienced ever warm, ever wet subtropical to tropical conditions ideal for the abundant growth of plants such as tree sized ferns.

   At the same time peat was accumulating, the continents of Laurentia and Gondwana were converging, resulting in the uplift of the eastern margin of what is now North America. Simultaneously, the Appalachian Basin was being formed to the west of the highland. Over a period og more than 20 million years, thousands of feet of sediments, including many layers of peat, were ultimately deposited in the Appalachian Basin.

   The ultimate nature of coal that formed was influenced by conditions that existed within the swamp during the formation of peat, including the mix of plant materials, the chemistry of swamp waters, and the drainage of the swamp where the plant debris accumulated. Once the peat was buried thousands of feet below the surface, temperature and pressure that at depth initiated the process of coalification. Of the two parameters, heat was the more important. Heat flows constantly from deep within Earth, a phenomenon called the geothermal gradient. The combination of depth and burial, duration of burial, and heat resulted in creation of different ranks of coal. Coal rank progresses from the lowest, lignite, a soft brown coal, to sub-bituminous and bituminous coal to the highest rank, anthracite.