THE MINING AND QUARRY INDUSTRY IO7 



MARL 



Under this head are inckided the soft pulverulent or loosely aggre- 

 gated deposits of calcium carbonate. They have the essential char- 

 acters of limestones, from which they are distinguished by their 

 unconsolidated character and somewhat greater content of mechanic- 

 ally absorbed water. 



The marls of New York State are of recent formation, being 

 associated with superficial beds of clay, sand and peat which have 

 been laid down during the Quaternary period. Swampy areas and 

 the basins of drained lakes frequently contain deposits. Wherever 

 bodies of standing water have existed, the dissolved lime brought 

 in by tributary springs and streams may have had opportunity to 

 precipitate, a process that is facilitated by evaporation as well as by 

 increased temperature of the water. In some cases lime is deposited 

 directly by springs and rivers owing to loss of the excess carbon 

 dioxid which holds it in solution. Its precipitation as an incrusta- 

 tion on vegetable growth, such as grasses and mosses, leads to the 

 formation of tufa or travertine. Marls almost always contain the 

 common varieties of shells found, in fresh water and at times these 

 are so abundant that whole beds are largely composed of their 

 remains. 



The most extensive marl deposits are found in the central and 

 western parts of the State. The frequent occurrence of limestones 

 in the underlying geologic formations of this section has supplied 

 abundant calcareous material for solution by ground waters. More- 

 over the drift and clays at the surface contain much lime in a com- 

 minuted easily soluble condition. 



Marl serves many of the purposes for which limestone is com- 

 monly used. As a rule it contains a higher percentage of calcium 

 carbonate than limestone and is correspondmgly freer from mag- 

 nesia, siHca, alumina and other impurities. It is, therefore, well 

 adapted for Portland cement manufacture. When briquetted and 

 burned it yields an excellent lime. Marl is also employed as a fer- 

 tilizer either directly or as a filler in artificial fertilizers an4 in the 

 manufacture of whiting and carbon dioxid. 



Distribution. In Madison county marl occurs in the marshy 

 tracts south of Oneida lake. Cowaselon swamp extending west 

 from Canastota contains several thousand acres of marl deposits 

 which are in most cases covered by peat. The beds are said to 

 reach a thickness of 30 feet. 



Marls are extensively developed in the swamps and lakes of Onon- 

 daga county, particularly in Fabius, TuUy, Camillus, DeWitt, Man- 



