Marlboro

Motorists travelling the Yellowhead Highway have wondered why a lonely chimney rises 56 metres above the muskeg near Marlboro, 35 kilometres west of Edson. This is the site of Alberta's first cement plant and the smokestack is a reminder of a dream that fell short of its goals.

The plant was built in 1913 by the Edmonton Portland Cement Company. This site was chosen because of the nearby extensive marl and clay deposits and its closeness to the Grand Trunk Pacific Railway. Marl was once used as a major part of cement.

Marl is a soft, crumbly, fine-grained limestone (calcium carbonate) that forms only in fresh waters. The Marlboro region has areas of high relief, and as groundwater moves through these higher hills it dissolves limestone fragments in the glacial deposits. This lime-rich water trickles out as springs near the sloughs and ponds adjacent to the plant.

As the spring water warms, it can't hold as much carbon dioxide and calcium carbonate (marl) is precipitated. It is further increased by animal and plant activities that change the carbon dioxide and calcium concentration in the water.

Marl can be used as a livestock feed supplement, as a treatment for acidic soils, or in cement.