MARYLAND GEOLOGICAL SURVEY 



FlG. I. CRYPTOZOON REEF AT BASE OF CONOCOCHEAGUE FORMATION, EXPOSED ALONG 

 NORFOLK AND WESTERN RAILROAD ABOUT ONE MILE SOUTHWEST OF ANTIETAM STA- 

 TION, MARYLAND, PHOTOGRAPH ABOUT ONE-FIFTEENTH NATURAL SIZE. 



FlG. 2. CRYPTOZOON STRUCTURE IN UPPER PART OF CONOCOCHEAGUE LIMESTONE EXPOSED 

 ALONG WESTERN MARYLAND RAILWAY, ONE-FOURTH MILE WEST OF CHARLTON MARYLAND 

 PHOTOGRAPH ONE-SIXTH NATURAL SIZE. THE OOLITES HAVE BEEN OUTLINED IN' INK 



