GYPSEOUS EARTH OF PAMUNKEY. 481 



neighbourhood. Still, I believe that gypsum is the principal ma* 

 nuring principle and that these wonderful effects will therefore 

 be confined mostly to clover (or other leguminous plants), during 

 its temporary action. The remains of bones and teeth also are 

 more numerous in this olive earth (immediately above the marl) 

 than anywhere lower; and hence this layer, apparently, is better 

 supplied with phosphate of lime -a manure of very great and 

 peculiar value for other crops, and especially for wheat. 



All these different beds, or thinner layers and varieties, of this 

 great eocene formation, except the high yellowish layer (), con- 

 tain either a considerable or a large proportion of green-sand 

 and of course some little potash which, as chemists inform us, is 

 a universal though small proportion of green-sand. Also, from 

 the very general indications either of white and tasteless efflores- 

 cence, or of manifest sulphuret of iron, or both, I infer that gypsum 

 also is a very general, if not a universal ingredient, to some amount. 



Until within the few latter years, all the various layers and 

 qualities of the whole eocene formation, were confounded in com- 

 mon understanding and parlance, through this neighbourhood, under 

 the one name of " marl." The green or gypseous earth was used 

 indiscriminately with the calcareous marl, by those proprietors who 

 had both exposed by the same excavations, without their looking 

 for or observing any difference of operation. The existence of this 

 strange error, and its general continuance (in this neighbourhood) 

 for eight or ten years, can only be accounted for by the following 

 circumstances : The two different layers were generally obtained in 

 the same excavations, and were more or less mixed in use and 

 never kept entirely separate for experiment : The soils (of Pamun- 

 key low-ground) being mostly or nearly neutral, did not exhibit 

 much effect from marl on the earlier grain crops, (as acid and much 

 worse soils would have done ) and when clover followed, the great 

 benefit which that crop always received from the large quantity of 

 gypsum in the green earth, even if with very little admixture of 

 calcareous matter, would make nearly as much show on that crop 

 as the marl alone. And before these early and transient benefits 

 of gypsum would be ended, perhaps another slight dressing of 

 marl would be applied, or some other treatment which would help 

 to conceal the respective operations of these different manuring 

 earths. 



But more lately, no farmer of this neighbourhood has deemed 

 the green earth worth applying as manure, if he could obtain 

 marl. Still, some who have easy access to thd former only, have 

 begun its use within the last few years, and so far, they report 

 encouraging results which the gypsum, with very little shelly 

 matter, can furnish for a few years. And so inveterate is esta- 

 blished error, that some other farmers, even to this dav, would 

 41 



