230 CALCAREOUS MANURES— APPENDIX. 



Carbonate of lime 4 



Green-sand 46 



Gypsum •-. \.. 3 



Silica and alumina 50 



100 



The next important locality of marl, and perhaps the most interesting, 

 is South Wales, Hanover, the farm of Mr. William F. Wickham, and which 

 is the highest point of its known existence. Here, as at the western ter- 

 mination of the green-sand in Petersburg, the bottom is seen, the under-ly- 

 ing stratum being gravelly sand mixed with rounded pebbles. This marl, 

 as seen in several places where very large excavations had been made to 

 marl both the South Wales and North Wales farms, differs altogether in 

 appearance, and greatly in constitution, from all the kinds below. The 

 bed is about 10 feet thick, is generally of uniform dark (nearly black) color, 

 except for being intermixed throughout with large fragments of white 

 shells, /it one place, the upper stratum of the marl is yellow or pale 

 reddish instead of black, but similar in the appearance of shells. Speci- 

 mens of these marls carefully selected on the places in 1840, and analyzed, 

 gave the following results : 



From South Wales, (William F. Wickham's land,) Hanover county, 

 100 grains of upper stratum, yellowish, consisted of 



Carbonate of lime 36 



Silicious sand and green-sand together 47— of which green-sand 



appeared to be one-tenth or • - 4.70 



and silicious (or quartz) sand 42.30 



Yellow clay and loss - - 17 



100 grains blackish marl, lying below the last — 



Carbonate of lime 44 



Green-sand g 



100 grains similar to the last, from a different digging — 



Carbonate of lime 32.50 



Green-sand 22 



From North Wales, Caroline county, Williams Carter's land, 

 100 grains of like blackish marl contained — 



Carbonate of lime ........ 37 



Green-sand 24 



These specimens, which were supposed to present a fair average of the 

 whole body, show an unusually large proportion of carbonate of lime for 

 the Pamunkey eocene beds, and a less proportion of green-sand. To the 

 happy combination of the two manures, I cannot but "ascribe the remark- 

 able success of Mr. Wickham in fertilizing his land. Still, he deems the 

 green-sand ingredient of so little worth, compared to the calcareous, that he 

 he would prefer that his marl should have had none of the former substance, 

 provided an equal quantity of calcareous matter could be substituted. 



In a former publication, I have presented at length both the facts and 

 my opinions of the peculiar operation of the green-sand marls of the Panmn- 

 key."*-' It is therefore enough to say here, that the operation of this compound 

 manure is greater than of any quantity of either one of the two enriching 

 materials of which it is composed. In smaller quantity than is usually applied 

 of calcareous marl, it produced equal or greater effect, and was more espe- 

 cially beneficial to clover. The heaviesr quantities also applied (as in the 

 practice of Mr. Wickham,) caused no loss; though the like large quantities 



• See more full statements at pp. 679 to 691, vol. viii. Farmers' Register. 



