SHELLS IN MARL. 171 



A largo supply of marl may be found in at least two places in Charleston, in the west part of the town. 

 One of them is upon Pensioner's Pond. 



In Salem, upon the west side of Salem Pond. 

 In the west part of Morgan. 



In Holland there are two or more heds of marl in the west part of the town, and there is one in the east 

 part of the town. One of them is on the road between Morgan and Stanstead, C. E., upon a beaver mead- 

 ow from five to seven acres in extent. The marl is beneath peat, and is from 2 to 3 feet thick. When 

 the peat is 2 feet thick the marl beneath is also 2 feet thick, and when the peat is 3 feet thick the marl 

 beneath is three feet thick. The marl rests upon blue clay and a clayey gravel. This is one of the best 

 known beds of marl in the State. 



FlG 77 Fig. 77 represents the peat, marl, and underlying sand of a marl bed in Derby. 



There are two beds of marl in the town. The one on the land of Mr. Willey, 

 near Derby Center, is one of the largest in the State. 



The deposit in Monkton has already been described. It rests upon the Red 

 Sandrock. 



In Grand Isle, upon the land of Mr. Pearl, in the northeast part of the town 

 about half a mile from Lake Champlain, there is a bed of marl. It occupies a 





Marl Bed in Derb basin about forty rods long and twelve wide, 100 feet above the lake. Peat 2 



feet thick overlies it, and its thickness was not ascertained. It appears to be 

 entirely composed of shells, of which the greater part belong to the genus Planorbis. 



In the northwest part of Alburgh, upon the farm of Judge Lyman, there is a bed of marl Fm - 78. 

 covering forty acres of surface. Fig. 78 represents its position and thickness. The blue 

 clay beneath is the upper member of the Champlain clays. The locality is very near Canada 

 line, about one mile from Lake Champlain. The upper stratum of the marl, in contact 

 with the peat, is composed of shells, mostly entire, of the genera Planorbis and Lymnaea. 

 The shells become more broken or pulverized in descending into the bed, and at the depth 

 of 2 feet few are seen. 



Messrs. Hall and Thompson mention a bed of marl in Highgate, but without specifying 

 the locality particularly. Sec - in 



We doubt not that the number of marl beds in Vermont is more than double of this 

 catalogue. 



Genera of mollusca inhabiting the marl ponds. We regret very much the loss of the 

 information concerning the mollusca inhabiting the ponds beneath which the beds of 

 marl are found, which was obtained by Prof. Adams. No man was better qualified to 

 name these different species, and draw from the facts interesting inferences. We have 

 reason to suppose that his information on this subject, if made public, would have con- 

 tributed largely to our knowledge on this important subject. In Monkton Pond alone, 

 he found eleven species. Since the re-organization of the Survey in 1857, no one has 

 examined the beds of marl with such care as was exercised by Mr. Hall ten years previous. 

 All the specimens he procured, however, from which we might have drawn interesting 

 conclusions, were destroyed in the burning of the State House in 1857. 



All the shells which are found in the beds of marl, belong to living animals. They 

 belong chiefly to the following genera of mollusca : Paludina, Lymnsea, Physa, Planor- 

 bis, Pupa and Cyclas. We have no means of saying how many species of these genera 

 are common. 



