256 PHYSIOGRAPHY AND GEOLOGY OF THE COASTAL PLAIN PROVINCE. 



Numerous samples of the marl have been taken from all points over 

 the property and carefully analyzed with the average results given in 

 columns I and II below. 



Analyses of marls from the Colonial Portland Cement Corporation's 



projicrhj. Grove, Va. 



Constituents 



Silica (SiO.) 



Alumina (AI0O3) 



Ferric oxide ( FeoOs) 



Calcium carbonate (CaCOj) 



Magnesia ( MgO ) 



Water (H^O) 



"Average of 3 analyses. 

 ?>Average of 6 analyses. 



By a simple process of crushing and screening the high silica in the 

 marl is lowered and the calcium carbonate increased. Two different 

 samples of the marl subjected to the above treatment gave the following 

 results on analysis : 



Analyses of marls from the Colonial Portland Cement Corporation's 



property. Grove, Va. 



Constituents 



Silica (SiO.) 



Alumina (AI2O3) 



Ferric oxide (Fe^Os) 



Calcium carbonate (CaCOs) 



Magnesia ( MgO ) 



Water (H^O) 



IV 



53.14 

 8.63 

 6.16 



35.53 

 1.14 

 4.55 



I and II. Calcareous portion of two samples of marl obtained from crushing 

 and screening. 



Ill and IV. Clayey matter obtained from the two samples of marl as part of 

 the same screening operation. 



From a mixture of the two portions separated by screening (calcareous 

 and clayey) a 30-pound sample was mixed and burned in a furnace, 

 cooled, ground and tested by standard methods. The material responded 

 well to all tests, exceeding in each case the standard requirements of 

 Portland cement. It is believed therefore that the extensive nyirl beds 



