232 ANCIENT ALLUVIUM OK LATEST DRIFT FORMATION. 



still falling much short of what it will reach some year-s later. All 

 these fine lands, on James river (owing to their fresh-water allu- 

 vial formation), are destitute of the marl (of fossil sea-shells), 

 which is so generally abundant lying under the adjacent higher 

 lands. Still, nearly all have been covered either by marl water- 

 borne from other places, or by lime brought from Pennsylvania, or 

 burnt from purchased oyster-shells. The percentage of increase 

 in the crops, even after the full effect is produced by calxing, is 

 much less on these lands, than of the poorest acid soils. But the 

 absolute increase of crop, and also the profit compared to the ex- 

 pense of the manuring, on these neutral and especially the hazel or 

 " mulatto" soils, afber some years, are as great as the absolute in- 

 crease of product, and the profit, on any acid or other poor soils. 

 The original production, and even the much reduced production of 

 these best soils, was so much higher than that of acid soils, that 

 an improvement of 50 per cent, in the crops of the former may 

 well be a greater absolute increase and profit, than an increase of 

 100 or even 150 per cent, on much poorer lands. 



On all the other tide-water rivers of Virginia, there are flat 

 lands of like geological formation, and having general resemblance 

 to those of James river ; while all such, on each different river, 

 have still more of general similarity of character to each other, 

 and of general difference from such lands on other rivers. Such 

 results might be inferred, from the great sources and materials of 

 the ancient alluvium having been different on each of the rivers. 

 Such lands on the Pamunkey river are the most extensive, the 

 most elevated (being in most cases full 30 feet above the present 

 level of the river, and far above the highest freshes), and also the 

 most valuable. Not much of this land is as clayey or was as rich 

 originally as the smaller extent of best lands on the tide-water of 

 James rivqr. But for ease of tillage, and cheapness of improve- 

 ment by marl, and for profit on the capital and labour employed, 

 no lands are superior. Since the beginning of 1844, I have been 

 a proprietor and cultivator of a farm of this description, bordering 

 on the Pamunkey (Marlbourne) ; and within the next seven years, 

 applied marl to the amount of nearly 370,000 bushels. The in- 

 crease and profits therefrom have already much exceeded my pre- 

 vious expectations ; though both (from the lateness of the manur- 

 ings) are still much below the mark they will reach, when time 

 enough shall have passed to bring the manure into full operation. It 

 is proper, however, to state that the marl used on the Pamunkey flats 

 is the green-sand eocene of peculiar character, and of more 

 than the beneficial operation of mere calx, or carbonate of lime. 

 It is indeed not rich in calcareous earth (having from 25 to 30, 

 and very rarely 35 to 40 per cent.); but, in addition, it contains 

 Borne gypsum, and a considerable proportion of green-sand. And, 



