WAUPACA COUNTY NEWS

August 24, 1923

 

Marl, In Addition Being Crop Aid Good for Roads

 

            The marl beds of Wisconsin, which have been hailed as the salvation of the sandy and acid soils of the state, may be utilized for building roads as well as for multiplying crops.

            The use of marl as a road material is in its infancy, but the few experiments that have been made are believed by E.F. Bean, geologist of the state highway department, to justify further investigation.  Marl deposits are found in many sandy regions where other good road materials are scarce.

            Until now, marl has been utilized as a fertilizer and corrective of thin or acid soils.  Chemically, it is carbonate of lime, usually with a small percentage of magnesium.  Its essential constituent is calcium carbonate.  In other words, it is limestone, pulverized.  It has been tested as a farm fertilizer in Waupaca and other counties sufficiently to give ample evidence of its worth.  Grain or alfalfa fields, treated with marl, are so different they seem to have been grown in a world far removed from adjacent fields not so treated.

Originated With Glacier

            Marl has an interesting chemical and geological history.

            It is probable that the huge glaciers, which, about 50,000 years ago, planed down the surface of the state, ground up large quantities of lime rock.  This pulverized lime rock was mixed with the clay and sand the glaciers left in their wake when they retreated to the arctic regions.

            Rain water, infiltrating the soils, took up the powdered lime, held it in solution, and carried it through underground spring courses to lake beds, some of which have since dried up.  Under the pressure of its subterranean courses the water held large quantities of carbon dioxide – the gas which provides the “fizz” at soda fountains.  The presence of this gas enables the water to hold much more lime.  The coolness of the water also helped.

            When the spring water flowed into the lakes the escape of the carbon dioxide and the warmer temperature of the lakes caused it to deposit the lime and, in many thousand years, the marl beds now found were built up.

Water Life Aided

            Vegetable and animal life in the lakes also facilitated the deposit of marl.  Chara, also known as stonewort, was one of the important workers in building marl deposits.  Plants, whether growing above or under water, absorb carbon dioxide from air or water, and replace it with oxygen.  Under water, this process, extensively carried on by chara, precipitates calcium salts.  This precipitation created other great marl beds.  Certain mollusks do the same thing.  This is shown by some marl deposits, which are filled with the shells of the little creatures.

            Now that he marl beds are here and are being discovered in the dried up beds of former lakes and in existing lake beds, it seems that plenty of use will be found for the materials they provide.

            In Minnesota, where experimental roads have been built of mingled marl and sand, the results have been encouraging.  In general, the tests show a marl-sand surface is satisfactory as a slab to hold the weight of traffic from breaking through into the subgrade.  This surface withstands heavy rains without injury, in fact it seems at its best under frequent rains.  The mixture forms a smooth surface without waves or chuckholes, a surface which as a resilience much more pleasing to the traveler than the usual rigid, hard surface.  It is not believed frost will injure this surface.

Dusty in Dry Weather

            One criticism of the road thus built is that under protracted dry weather and under heavy traffic the surface becomes dusty, though light traffic produces little dust, even in prolonged dry spells.  The dust nuisance has been checked by spreading a coat of fine gravel about an inch thick over the roadway, or occasionally giving surface treatments with calcium chloride.  This substance absorbs moisture from the air and allays the dust and it is said to be even better than the gravel coat.  The results in Minnesota were so satisfactory that renewed efforts are being made to find marl deposits near highways.

            In Wisconsin, marl deposits have been found in the territory east of Madison and south of Portage.  Several marl lakes exist in Waupaca and Waushara counties.  Soundings show that Lake Mendota, the northern boundary of Madison, rests on a marl bottom.  The same is believed to be true of Lake Monona, and other lakes in the region of Madison.  Some of the marl s in the sand belt where it will be particularly useful both as a fertilizer and a road material.