4 Report on the projected Survey of the State of Maryland. 



Taking this view, then of the constitution of the soil, in connexion 

 with the well known fact, that to constitute a permanently good soil, 

 there should necessarily be present in it a due proportion of silicious, 

 argillaceous and calcareous particles ; and, in connexion too with the 

 fortunate circumstance of the existence of the immense deposites of 

 shell marl, which have just been referred to, the undersigned remain 

 persuaded, that the system of geological investigation, to be pursued 

 ibr the Eastern shore of Maryland, in so far as its agricultural inter- 

 ests are concerned is a very simple one. It must consist — 1st, in 

 ascertaining and then delineating upon a map, the extent and limits of 

 each class of soils ; and 2dly, in discovering the position and ascer- 

 taining the extent and nature of the deposites of shell marl. 



In reference to the latter subject of investigation, it must be borne 

 in mind, that, as already stated, the value of this marl as an amend- 

 ment to the soil will depend upon the species of shells which it en- 

 closes, the facility with which those shells are susceptible of disinte- 

 gration, and the nature of the cement by which they are sometimes 

 held together, or the nature of the mineral deposites with which they 

 are associated. Thus it has been found, that those beds, which con- 

 sist principally of clam shells usually associated with numerous varie- 

 ties of other smaller bivalve and many univalve shells, and containing 

 very little admixture of foreign ingredients, yield a marl which ex- 

 hibits its beneficial effects upon the soil in a very short time ; be- 

 cause the calcareous particles are derived from shells which are very 

 prone to disintegrate when exposed to the atmosphere. Marl beds, 

 composed entirely or principally of oyster shells, are much less valu- 

 able, because of the slow disintegration and decomposition of this 

 species of shell. Scallop shells, which are a species nearly allied to 

 the oyster, resist such decomposition still more obstinately than do 

 oyster shells, and when they occur, as they have been observed to 

 do, in extensive beds firmly agglutinated by an argillo-ferruginous 

 cement, they are useless in all soils, and may be positively injurious 

 to some. The undersigned have had abundant opportunities of as- 

 certaining, that beds of shell marl, thus constituted, occur in various 

 localities, on the Eastern shore of Maryland — sometimes as distinct 

 uniform deposites, but more generally in alternating strata, which 

 might be described as so many varieties of shell marl ; the indis- 

 criminate use of which has given occasion to some mortifying disap- 

 pointments. 



