r);ts 



MESOZOIC FLORAS OF IMTEI) STATKS. 



Nm rfprvsiente*! CTT. feeC. 



Stmtirled sands and clays, chiefly '=-_- 



redt'im^ltcd from tlic mnierly- -= 



\ng Kappaliaiiiiock ttt^l-i. Fossil ^ 



plant? in tht* clay scciiii.. larirely = 



dicotyledODg. Typical ."pt-cies; ^ 

 Sapindttpvis variabilis. 



Mount Vernon bw»» l Chocolate clays 

 ' iS fe*t. I PnpultiM imtftMiti-fh 



Heavy livds oT coarse, ft-ldspathic, 

 gray or white »aiids and (Travels 

 (arkose> hardenlntf into rock 

 (freest'tnei; vuryintr t<t some- 

 what pure, cross-ln-ddcd eutnd^ 

 with worn <|iiartz and other pcl)- 

 bles. contttlninu Iwds of ilarkday 

 of varying dimi-nslmis, always 

 Icntictilar and often reduced t'> 

 ' fuiMll leniies. poi-ketH, hulls, ami 

 l>ellct»; the clay liK'nltlc innl 

 often abundantly plant-bearirt^. 

 Typical Hpecleet: DtoimiU'K Jinchi- 



Sand or sandstone with rocks, 

 brown or while or purple, of leu i 



quartzitic. ' 



Stratillfd sands and clays, tlie ' 

 former often thick and of tine 

 quality; the latt«.-r in thin 

 seams and plant-bejirin^'. often 

 hhn'k and representinw forest 

 beds niU'd with comminuted 

 ve^'ctahb- matter and impure 

 liir'iite, and occasionally con- 

 tiiiniiit,' amber. i 



\.i\s and sands, imperfectly 

 stratilied. often highly colored 

 with oxide of iron, forminpr 

 commercini paint stone and 

 paint clay ; cycadean trunks 

 and other vegetable remains, i 



Plastic or arenaceous 1 Federal I 

 clays, Vitiphyllttm i Hill beds. , 

 vntUijidtiiu. 1 50 feet. 



Heavy beds of cross -bedded 

 sands, sometimes fcldspathic. 

 i"re(iuently indurated and 

 stained red \>y oxide vt iron. 

 llUi-il uiih leiriiuiniMis crusts; 

 the sjinil~i'intniniii(; numerous 

 tar;,'e day pockets, often dark 

 and li^nitic, abounding in nod- 

 ules of Iron ore (carbonate of 

 iron I, often very pure i white 

 ore); plant bearing icycads): 

 Athrotaxopsis exftausa. ('((trfo- 

 jfhlfbit* acuta, etc. 



Fig. U.— Columnar section ol the Potomac formiitiou. 



