454 EOCENE MARL. 



of, and have reported the effects,* in comparison with either lirae 

 or miocene marls, the expense and trouble were so great, that it is 

 now considered by some of the most judicious farmers on the tide- 

 water rivers, that they can better afford to buy stone-lime, at its 

 present low price (8 to 10 cents the bushel), than to transport 

 marl of any kind by water. This, however, is an erroneous esti- 

 mate. A bushel of such marl is worth more as manure, than a 

 bushel of slaked lime (though slower in operation), and can be 

 transported twenty to forty miles by water, and delivered for 4 

 cents the bushel. 



Since the foregoing pages were written, I have learned of two 

 farther exposures of this body of eocene marl. One is four miles 

 north of Evelynton (in Charles City county), where the marl was 

 reached and penetrated by the digging of a well in 1814. At 

 about thirty feet deep, after passing through the marl, and a layer 

 of rock, water was reached, which rose to the top of the well, and 

 continues to flow over, forming the only Artesian well known in 

 this region. The other locality is in Henrico county, on Turkey 

 Island creek, its eastern boundary, and about eight miles north of 

 City Point. This marl I recognised to be the same, by a specimen 

 recently brought me for examination. It is below the surface of 

 swampy ground, and is coloured dark gray. It is much fuller of 

 green-sand, and indeed in that respect makes some approach to the 

 green-sand marls of the Pamunkey, of which the nearest exposure 

 is only sixteen miles from this place. It is probable that the marl 

 extends continuously from the one place to the other, and may be 

 found throughout the interval by deep digging.f 



(e) The Gypseous Earth or Green Earth of James River. 



Before proceeding to consider the next and only remaining 

 known variety of our marls, the eocene green-sand marl, it is ne- 



* See Farmers' Register, vol. v., pp. 189, 247, 511. 



f After the publication of this report, I first learned, from the examina- 

 tion of hand specimens, that eocene marl was exposed on the new railway 

 route between Fredericksburg and the Potomac river. The specimens ex- 

 hibited to me were very hard, and seemed (to the eye) to be also poor. 



The most extensive, rich, and valuable body of marl, of the Atlantic 

 States, is eocene, and which I first knew, and then examined extensively, 

 during my Agricultural Survey of South Carolina, in 1843. This im- 

 mense body extends across lower South Carolina, and also the connected 

 parts of both North Carolina and Georgia. The bed is full 300 feet thick 

 under Charleston, and of unknown depth elsewhere. It contains usually 

 from 65 to 90 per cent, of canbonate of lime has but few whole or distin- 

 guishable fragments of shells remaining and is of more homogeneous 

 appearance and firm or stony texture than any other beds of marl. 



