The History of Coal Mining in Lethbridge

A long time ago southern Alberta and a large part of the prairies were covered by shallow seas and swamps. It was home to many prehistoric birds, reptiles, and semi-tropical forests. This made it an ideal environment for the formation of coal. As plants died and then decayed in swampy water, thick layers of dead vegetation accumulated. Ordinarily, bacteria break down such organic matter, but in this swampy water the dead vegetation was only partially broken down. The accumulation of plant matter at the bottom of the swamps led eventually to the formation of an early form of coal called peat. Peat is composed of roughly 50% carbon, with the other half being a mix of oxygen, nitrogen, hydrogen, and ash. This peat accumulated at the rate of about 28 centimetres a year.

P19640894000-GA, A double pointed pick of the type used in the mines between 1900-1910.

This process would continue for many years and create large amounts of peat. Eventually the swamp would be covered by the changing course of a river or sea. Whenever changes like this occurred, the swamp would be covered by many layers of sediment. As the sand and soil piled up over the peat, it was subjected to great pressure and heat, as well as a lack of oxygen. Over time these conditions transformed the peat into coal. Usually one metre of coal was produced for every 20 metres of peat. In the Lethbridge area this process occurred about 70 million years ago, during the Cretaceous and Tertiary periods. It left the region with a seam of medium-carbon, high-volatile "c" bituminous coal, ranging in thickness from 1.2 to 1.8 metres.

Ranking of Coal