1836.] 



FARMERS' REGISTER. 



(571 



place, its height declines until no portion of it is 

 any longer visible above the water edge. 



Eocene Deposite of the Potomac, Rappahannock, 

 and Maltapony, Sfc. 



Although the shores of these rivers have as yet 

 been but little examined '.vith a view to the struc- 

 ture and arrangement of the various strata they 

 exhibit, enough has been observed to prove that 

 they are no less rich in t lie Eocene marl than the 

 other districts which have been described. On 

 Potomac creek, and for a great distance below 

 its mouth, the green sand strata may be seen run- 

 ning along the base of the cliff; and from speci- 

 mens examined, there can be no doubt that the 

 character of the deposite is similar to that of the 

 Eocene of the James River and Pamunkey. On 

 the Rappahannock, for a considerable distance 

 below Port Royal, the very same appearance is 

 presented; and the green sand obtained from some 

 of these localities is in every respect like that from 

 the points already noticed. In some places on the 

 Mattapony, the occurrence of the green sand stra- 

 tum has been ascertained, while in others the 

 beds containing this substance are replaced by 

 beds of clay, which, though geologically of the 

 same (or Eocene) formation, are yet less likely to 

 prove interesting to the agriculture of the vicinity. 

 Minute inquiries throughout all this district, and 

 throughout the corresponding region south of the 

 James River, are alone capable of developing the 

 extent and value of this deposite. Even a great 

 deal yet remains to be done in investigating local- 

 ities on the James and Pamunkey Rivers, the 

 northern shore of the latter being so far almost un- 

 explored, and the precise character and value of 

 some of the beds in localities examined being but 

 imperfectly ascertained. 



Of the several beds composing the Eocene formation. 



In treating of the accompanying Miocene in the 

 beginning of this section of the report, our descrip- 

 tions have been confined chiefly to those beds 

 which occur remote from the rivers upon the high- 

 lands, and no mention has been made either of the 

 white friable sand or olive colored clay already 

 frequently noticed in describing the overlying stra- 

 ta on the Pamunkey. 



The first of these, though once the repository 

 of shells and other fossils, is now entirely desti- 

 tute of carbonate of lime. A small quantity of 

 gypsum in a minutely divided state seems to be 

 its only ingredient of any value, and the amount 

 of this present in the specimens I have examined 

 is much too inconsiderable to give the material 

 any agricultural importance. 



The olive earth, which is frequently an exten- 

 sive layer, has also lost all the calcareous matter 

 which it once contained; but a further examina- 

 tion, chemical and geological, of this material, will 

 be required before its nature can be exactly de- 

 termined, or the possible applications of which it 

 may admit can be ascertained. 



The upper bed of the Eocene, characterized in 

 most of the localities by the gypsum which it con- 

 tains, is worthy of especial consideration on ac- 

 count of this valuable ingredient. In specimens 

 from the James River, from five to eight per cent. 

 of this substance has been found in a divided state, 



at the same time that a considerable additional 

 quantity in a massive form exists in various parts 

 of the same stratum. 



On the Pamunkey this stratum is not so thick, 

 and is perhaps less abundant in the sulphate of 

 lime. The lower beds, in some cases containing 

 a marked proportion of shelly matter, and in 

 others having almost none, are more especially 

 distinguished by ihe larger proportion of another 

 and even more important ingredient, to wit, the 

 green sand. Both on the James River and Pa- 

 munkey, their richness in this material gives them 

 an agricultural value which perhaps no proportion 

 of calcareous matter by itself, however great, 

 would be able (o impart. The illustrations of its 

 beneficial effects, and the general observations 

 upon its employment as a manure or marl, which 

 will hereafter be presented, will, I think, manifest 

 the justice of this opinion, and give a sound confi- 

 dence to those who are disposed to make trial of 

 its powers. 



Extent and commodious position of the Eocene on 

 the rivers. 



One of the most interesting facts presented in 

 the foregoing description of the Eocene on the 

 Pamunkey and James Rivers, is the great depth 

 and extent of those strata, which, from the nature 

 of their contents, may be applied to profitable use 

 in agriculture. Beds of such materials, preserv- 

 ing an average thickness of twenty Jeet, extend 

 along the banks of the Pamunkey with occasional 

 interruptions for more than twenty miles. 



Their position on the river shore makes them of 

 most convenient access, and gives additional fa- 

 cilities to the conveyance of the fertilizing mate- 

 rials they furnish to various distant points, while 

 from the peculiar character of the strata them- 

 selves, they are almost exempt from the usual de- 

 structive agencies of the freshets, being of a tex- 

 ture to withstand, with scarcely any loss, the most 

 violent assaults of the sweeping currents by which 

 the banks of the river are so often overflowed. 

 To this cause we are to ascribe the steep declivity 

 of the shores in many narrow parts of the river, 

 where the abrading action of the water, instead of 

 rapidly carrying off the materials of these strata, 

 has merely served to wear them into smooth and 

 almost perpendicular precipices rising immediate- 

 ly from the margin of the stream. 



Existence of the Eocene beneath the highlands, and 

 throughout the whole breadth of the state. 



The general position and direction of the Eo- 

 cene beds suggest another view of great practical 

 importance to this and the neighboring districts of 

 the states. I allude to the probable, perhaps I 

 may say certain, continuation of these strata over 

 a wide area, on a level corresponding to the gen- 

 eral depth at which they are found upon the ri- 

 vers. In confirmation of this view it may be re- 

 marked, that since the publication of a communi- 

 cation on this subject in the Farmers Register, the 

 existence of a similar deposite throughout an ex- 

 tensive district of Maryland, lying in the general 

 direction of our Eocene formation, has been 

 brought to light, and there is reason lor believing 

 that within the borders of North Carolina, near to 

 the Virginia line, the same strata are displayed in 



