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Pangea

Always since the late 1990s, there'south been ane ascendant theory for how Earth's enormous coal reserves were created: Coal is the fossilized carbon remains of plants that died hundreds of millions of years agone.

The conventional explanation for why then much coal dates from a particular era in history (the Carboniferous menses) is that the plants from this period had simply evolved lignin. Lignin is a disquisitional back up construction in wood and bark, information technology makes prison cell walls rigid, and it allows for stems and branches. Because lignin was new, at that place were no leaner or fungi bachelor to break information technology down. Over fourth dimension, this thick layer of not-decomposing plant matter was compressed, baked, and transformed into coal deposits.

That'southward been the theory, at to the lowest degree — but a new Stanford newspaper argues that it's non true. Geobiologist Kevin Boyce, an associate professor of geological sciences at Stanford School of World, Energy & Environmental Sciences, argues that the evolutionary lag hypothesis doesn't fit the residuum of the geologic data. Many of the plants that grew during the Carboniferous menses had depression levels of lignin, and there'due south no clear link between lignin levels and the size or quality of coal deposits within the relevant geologic layers. Furthermore, given the estimated book of plants growing on World at the time, we would've laid down World'southward entire estimated coal reserves within a millennium — non the millions of years scientists causeless information technology took for lignin-eating microbes to evolve.

If coal formation wasn't linked to this detail constitute construction, why was most of our coal laid down at the same time (geologically speaking)? According to Boyce and his co-authors, the answer lies in the unique climate conditions and geological processes that existed at the time.

In the United States, we call our chunk of the Central Pangean Mountains the Appalachian Mountains.

In the United states, we call our chunk of the Key Pangean Mountains the Appalachian Mountains.

During the Carboniferous, the supercontinent Pangea was coming together. Shallow wetlands were common during this area, and the geological fault lines between the diverse continents created both mount ranges and deep basins as the continental plates ground against each other. Remnants of the Central Pangean Mountains, shown higher up, withal exist in the Appalachian Mountains in the United States, the Little Atlas of Morocco, and the Scottish Highlands.

"If you desire to generate coal, you need a productive environment where yous're making lots of establish matter and you lot also need some style to forbid that plant matter from decaying," Boyce said. "That happens in wet environments."

Because these basins and mountain ranges were created over millions of years, there was more enough time for plants to fill up the area, die, and so be replaced. This created huge deposits of organic fabric that was eventually transformed by heat and pressure into coal. The authors notation that the Appalachian mountains (known to be rich in coal) may have been created past precisely this process, every bit tropical wetlands sank into the buckled bedrock.

This theory could explicate why the Rockies are another coal-rich surface area. The coal beds in the western United States were laid down at a time when the climate in that region was wet and tropical. The aforementioned plate tectonics that created the Rockies also formed neighboring basins, perchance trapping organic fabric in the aforementioned fashion.