MARL BEDS. 169 



" The length of this period is strikingly illustrated in the Monkton marl bed. A long series of years 

 required to furnish shells sufficient for a single layer, and yet they have accumulated to more than ten 

 feet in depth. Twenty thousand years is a very moderate estimate for the time required at he present rate 

 of accumulation, and it is more likely to have exceeded this many fold." 



Before describing the occurrence of the marl beds of Vermont, we would suggest a word as to their ori- 

 gin. A part of the marls is probably a chemical* deposit. Carbonate of lime is scarcely soluble in pure 

 water, but is abundantly soluble in water impregnated with carbonic acid. Yet the excess of acid is easily 

 expelled, and then the salt will be deposited in a pulverulent form, unless there be some reason why it 

 should be crystalline. As marl beds chiefly occur in the vicinity of limestone, it is easy to surmise the ori- 

 gin of the carbonate of lime. The tributaries convey it in solution from the ledges into the pond. There 

 the constant evaporation of the water causes the dissolved portion to fall to the bottom. Mollusca add 

 their shells to the mass, and at length a thick deposit will be formed. When the pond is drained or dries 

 up, the marl may be gathered. 



Upon Plate II. we have represented every marl bed in the State, of which we have any 

 knowledge. We have learned more from the Reports of Rev. S. R. Hall, respecting their 

 localities, than from all other sources combined. It will be seen from Plate II, that these 

 beds are chiefly found in the eastern part of the State, or overlying the calciferous mica 

 schist. The surface underlaid by the metamorphic schists, extending through the middle 

 of the State, is entirely destitute of them. None of them are found except in the vicinity 

 of calcareous rocks. The following are the localities, beginning at the southern part of 

 the State and working northerly along the calciferous mica schist. 



At Brattleboro, northwest part, perhaps passing over the line into Dummerston. 



At Westminster, west part of the town, on the farm of Mr. Wilcox^ 



At Saxton's River Village, on the land of Mr. Leach, there is a bed of marl of unknown thickness, 



underlying a bed of peat four feet thick. The bed has been opened to a depth of four feet. 



In the southeast corner of Windham there is quite an extensive bed of marl, resting upon gneiss or 

 hornblende rock. 



In West Windsor a good deposit of marl exists on the land of Samuel Myrick. It contains about two 

 acres. And there is said to be another deposit in the neighborhood. 



In Woodstock, upon the farm of Hon. C. Marsh, there is a very valuable deposit of marl, covering from 

 twelve to fifteen acres. The marl is probably from six to ten feet thick, underlying peat. Here was a 

 small natural pond, very much enlarged doubtless by a beaver dam ; the muck is four feet thick above the 

 marl and of excellent quality. A supply of the best of lime may here be made for the county, and manure 

 for the town for ages. Mortar made from this marl is unusually strong. 



In Pomfret, in the north part of the town. 



In East Barnard, at a pond, there is a valuable bed of marl. Considerable lime has been manufactured 

 from it. The pond is small and will eventually dry up ; and the marl will become more available. 



In Royalton, three beds. One is in the east part of the town, the others in the west part along a branch 

 of White River. The most valuable bed is on the farm of Mr. Dewey. It was deposited in an ancient 

 beaver pond, and is now very accessible. It can supply lime for the whole White River valley. 



In the east part of Randolph. 



A small deposit in Tunbridge. 



Marl is found in several ponds in Brookfield. One of them is on the land of James Wilson. 



In Corinth there is a valuable deposit of marl from four to six feet deep, upon the land of N. Lovewell, 

 Esq. It lies upon blue clay and clayey sand. 



In William stown. One upon the farm of Jason Fuller has been described in detail already, on account 

 of the bursting of the barrier of the pond beneath which it was formerly located. We do not know whether 

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