528 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



SUCCESSION OF BED ROCKS. 



Pleistocene. 



Pliocene. 



Toro 

 limestone. 



c. River alluvium, 

 b. Muds and silts, 

 a. Gravel. 



J-Shell marl and limestone. 



Miocene. 





formation } Li £ nt colored tuff beds, argillite, etc. 



Gatun f C- CJay beds, 

 formation \ h - Pine sandstone, 

 lormation. 1 ArgUlite _ 



^Oligocene. 



|c. Sandstone. 



7 - formation p- Limy conglomerate, 

 loimauon. a _ Sandstone . 



Caimito 



6- limestone 1 } Marme limestone, many corals. 



5. formation 8 ' } Land formed clay rocks, lava flow, etc. 



4- formation } Marine carbonaceous shale, clay, tuffs, limy sandstone. 



o o °o° ol:> | 3. conglomerate [ Coarse and nne conglomerate and sandstone beds. 



' O <=> g ° 



Eocene? 



, Las Cascadas \Volcar,ic debris, mud-lava, some flows and dikes of 

 ^S_£^r^ g-^j • agglomerate. / andesite. 





*■ ^ S m°a&} Vol -- c ^ccia. 

 SUCCESSION OF IGNEOUS ROCKS. 



Miocene? 

 ;< Mostly). ' 



6. Basalt. 



lo D o°oS 5. Meta-breccia. 



4. Rhyolite. 



3. Andesite. 



(?) 



-i/\1 11 I 



/'li' 1 ' 1 '! 2. Diorite. 



1. Grandiorite. 



Pig. 26— Rock succession in the Canal Zone. (From U. S. Bureau of Mines Bull. 86.) 



