MARL. 
83 
MARL. 
Description. This substance is arranged by Cleaveland as a sub-species of carbonate of 
lime, of which indeed it is essentially composed. Some marls are more or less indurated, 
while others are friable and earthy. In some the argillaceous ingredient is comparatively 
small; in others, again, it abounds, and furnishes the predominant characters. The calcareous 
and argillaceous marls unite by imperceptible degrees, and the latter sometimes pass into 
clay. Marls, therefore, are sometimes arranged under the heads of calcareous and argillaceous, 
and sometimes under those of the indurated and the earthy. 
The term fresh water marl is applied to those accumulations which have been formed by 
the decay of successive generations of shells at the bottoms of lakes or ponds. In marshes 
that were once ponds, the marl is often covered by a deposit of peat, arising from the growth 
and decay of plants. 
The marls usually disintegrate or crumble by exposure to the atmosphere for a longer or 
shorter period, depending upon their nature. The same changes generally take place in a 
very short time when marl is immersed in water, with which it forms a short paste. It is 
probably to these properties that this substance owes its value as a manure. 
Composition. All marls effervesce with acids, sometimes very briskly and sometimes 
feebly, according to their solidity and the proportion of carbonate of lime, which may vary 
from twenty-five to eighty per cent.; indeed in the argillaceous marls it is often much less.* 
To ascertain the proportions of the ingredients of a marl, a known weight of it may be 
treated with dilute muriatic acid, by which the calcareous part will be dissolved ; and the 
residue, being dried and weighed, will give the amount of clay with sufficient accuracy to lead 
to correct conclusions in regard to its use as a fertilizing agent.f 
There are in this State many rich and extensive localities of marl, but their value does not 
appear to be appreciated. The following are more particularly deserving of notice. 
Albany County. In the towns of Bethlehem and Coeymans in this county, there are 
beds of marl of some extent, which contain from forty to eighty-five per cent, of carbonate of 
lime. They have not, however, it is believed, been much used for agricultural purposes. 
Cayuga County. According to Mr. Hall, the Cayuga marshes, which embrace an area of 
forty thousand acres, are in many, and probably in all places, underlaid by marl to the depth 
* Cleaveland. Elementary Treatise on Mineralogy and Geology. 
t According to Chaptal, “ Marl is principally composed of sub-carbonate of lime and alumina; the proportions in which these 
are combined constitute all its varieties. The lime contained in marl, as it is taken from the bed, is never saturated with carbonic 
acid; but after being exposed to the air, it becomes at length saturated with the acid it receives from it, crumbles and effloresces. 
The decomposition of marl may be hastened by frequently turning it, so as to allow the air free access to the lime ; and this me¬ 
thod is generally practised by those who employ marl as a manure.” Chemistry applied to Agriculture. Amer. Ed. p. 44. 
