MAKYLAXI) Gi:OL()(!ICAL STRVKY 



69 



Pleistocene. 



Eoceiiu. 



Kuet. 

 :i(J 



10 



III. Siition of' wtnlci'H /xirlion uf l)hi\}' <il .I'/nid Creek. 



Fine siiiul, ll!;ht-y<'lli)w in color, with wiiite (•liiy n<;iir tlie 

 base 



r Fine sand, of lifjlit-fjcreenisli color, containini,' a few ijlaii- 



j conitic fjrains (Zone 10) 



• j Tliick-hedtkul, arenaceous, and iclauconitlc limestone inter- 

 g stratilicd with unconsolidated layers of partially weathered 



^ I greensand, the indurated layers largely liUed with the 



sliells of Tin-rltvUii mortoin (Zone '.)) lO 



Fine sand, of gray or green color, containing several 

 irregular l)ands of TurriteUn mortoni, also T. luimeroxa, 

 ('uciilliicd f/iginitcd, Cnixxatcllitca (ihiefunnis and Os/rca com- 

 prcssiro.strd (Zone 8) 30 



C Dark-colored greensand, chiefly filled with broken shells of 



Mevetrix oraid rar. pyf/d and C'ranxdieUilcx alaeforiuis (Zone 7) 7 



Ditto, with same shells in whole condition (Zone 0) 1 



Indurated layer of light-colored greensand tilled with 

 Turritella mortoni, T. hnmeroxu, CrdsxuteUiteii ulaeformis, 

 Dosiniopsu lenticnlaria, Meretrix ovata var. pyga, Panopea 



eloiHi<tt<i, P/iohidomi/a nutrylfinrlirti (Zone 5) 2 



Greensand uiarl containing same forms (Zone 4). . . 8 



Indurated layer of dark-colored greensand with Crussatcllitcs 

 alaeformis, Jferetrix ovata var. pyga, Dosiniopnia lenticularis, 



and O.strea comprensirostra (Zone 3) 2 



Greensand marl with Dosiniopsis loilicidaris, Meretrix ovata 

 var. pyga and Crassatellites alaeformis (Zone 2) 16 



Total 112 



Pleistocene. 

 Neocene. 



Eocene. 



IV. Section of center of bluff at Potomac Creek. 



Feet. 



Fine yellowish sand containing red and brown bands 15 



White gritty clay, wath Miocene fossils at base 5 



Greenish-gray argillaceous sand, slightly glauconitic (Zone 



15) .'. . . r ' 38 



Argillaceous sand containing bauds of selenite crystals 



(Zone 14) ' 4 



Light-gray glauconitic sand Mith Venericardia potapacoensis 



(Zone 13) 3 



Greeuish-gray argillaceous sand (Zone 12) 8 



Indurated greensand with Venericardia potapacoensis (Zone 11) 1 

 Greenish-gray argillaceous sand, glauconitic, with casts of 

 l^ Meretrix (Zone 10) 25 



Thick-bedded arenaceous and glauconitic limestone inter- 

 stratifled with layers of partially weathered greensand, 

 the indurated strata largely composed of the shells of 



. ^ TurriteUa mortoni (Zone 9) 12 



a< j ° ' Greensand bed, much weathered in its upper portions, and 



a I ■- 



S ^ Ph-! 





tilled chiefly with TurriteUa mortoni in several thick layers ; 

 also T. Jiumerosa, CucuUaea gigantea, Crassatellites alaeformis, 

 Ostrea compressirostra, and many other species (Zone 8) . . . 25 



Total 136 



