The next up on the Drunk on Geology series is Coal Mine Tempranillo from the Coal Mine Vineyards.
Coal is a type of sedimentary rock that has a very high organic content. It is made up of prehistoric plant material that has slowly been compressed over time forming thin layers ranging from millimetres to several tens of meters thick. The large amount of plant material typically occurred in prehistoric swamps. Over time the plant material died and accumulated in the water. There was so much dead plant material in the water that there wasn't enough oxygen to cause plant decay, leaving the plant material behind to eventually be covered up by sediment as the swamp was slowly transformed into a different environment (i.e. beach, floodplain, lagoon, etc.).