CALCAREOUS MABL. 



249 



Analyses of Virginia Greensand Marl. 



Major Winston^ Aquia Creek* 



Hanover Stafford 



County County 



IPer cent JPer cent! Per cent. 



Waverly^ 

 Sussex 

 County 



Per cent. 



City Point* 

 Prince George 

 County 



Per cent. Per cent. 



SiOo combined . . 

 SiC uncombined 



AlA 



FeA 



FeO 



MgO 



CaO 



KoO 



NaoO 



PA 



HoO 



47.45 

 2.76 

 7.33 



12.03 

 9.43 

 2.90 

 0.57 

 5.75 

 0.42 



CO2 



Volatile at red heat 

 less CO; 



Total 98.49 



Siliceous matter . . 



9.85 



43.34 



8.22 

 6.62 

 15.16 

 8.33 

 0.95 

 0.62 

 4.15 

 1.84 



i6.32 



21.58 

 7.70 



1.05 



36.78 



0.37 



0.59 



0.09 



0.76 



(at 110°) 



29.79 



0.21 



Insol. 

 45.20 



5.22 



24.38 

 4.73 



1.80 



61.15 



2.19 

 1.36 

 3.85 



0.47 



56.03 



0.37 

 1.52 

 3.15 



99.55 



98 . 92 

 25.36 



0.05 



^Corse, M. B. and Baskerville. Chas. Analyses of Glauconite from Hanover 

 County, Virginia. Amer. Chem. Jour., 1892, Vol. XIV, p. 627. 

 ^Analysis by Peter Fireman of Columbia University. 

 ^Ellett, W. B., and Eskridge, A. T. Virginia Experiment Station Bulletin. 



CALCAREOUS (SHELL) MARL. 



The various Miocene formations of Virginia, especially the Yorktown, 

 contain extensive deposits of molluscan shells, and frequent fish and 

 mammalian bones. The marl beds usually attain considerable thickness 

 as well as lateral extent, and the percentage of lime in them is very high. 

 Analyses of the marls generally show a small amount of potash and 

 phosphoric acid. The percentage of lime in the beds depends largely upon 

 the amount of sand and clay present, forming the matrix of the beds, as 

 the shells are composed almost entirely of calcium carbonate. Some of 

 the marls contain as much as 97 per cent of calcareous matter. The 

 bones yield most of the potash and phosphatic material present, some 

 of the Miocene bones containing as much as 30 per cent of phosphoric acid. 

 The calcareous or shell marls owe their principal value, however, to the 



lime content. 



The large areal extent and high lime content of the A^irginia Miocene 

 shell marl beds render them of great commercial value for use (a) in 



