EOCENE GREEN-SAND MARL. 



475 



It may not be useless to note another point of recent resemblance 

 between these two manures, both' of which seem so capricious and 

 uncertain in operation in general. This year (1842), the applica- 

 tions of the green earth on the Coggins Point farm, whether made 

 in the beginning of the winter preceding, in March, or in the be- 

 ginning of summer, have acted more quickly and powerfully than 

 any known before. This I had ascribed to the earth being mostly 

 obtained from deeper excavations. But I have lately heard, from 

 Messrs. Hill Carter and John A. Selden, both extensive and ex- 

 perienced and successful users of gypsum, that they have never 

 before known the good effects of that manure to be so remarkable 

 as in all their applications of this year. 



(c7.) Eocene green-sand marl. 



Except in the lower stratum exposed in the pit recently dug at 

 Evergreen, this peculiar and valuable kind of marl has not yet been 

 known to me in Virginia elsewhere than on and near the borders 

 of the Pamunkey river; though there can be but little doubt that 

 this or other eocene deposits are to be found elsewhere than within 

 the limits here stated of the now known localities. It is more than 

 probable that other rivers cut through and expose some of the eocene 

 as well as miocene deposits; and that deep diggings would reach 

 them also in the intervening high lands. The Pamunkey eocene 

 formation is seen first, or exposed most south-eastward, at North- 

 bury in New Kent county; and it is found (either as marl or gyp- 

 seous earth) on nearly every farm above, to South Wales, in Hano- 

 ver, the farm of Mr. William F. Wickham, just below the junction 

 of the North Anna and South Anna rivers, and on North Wales, 

 the farm of Mr. Williams Carter, across the Pamunkey, in Caroline 

 county. This distance in a Straight line is about 22 miles ; and 



ment of our green-sand earth, as well as that of New Jersey ? Cleaveland 

 gives the following contents of three different kinds of chlorite, ascertained 

 by different chemists: 



Vauqueliu found a specimen of common talc to contain 27 per cent, of 

 magnesia. Cleaveland. 



