328 *" MEMORIAS DE LA SOCIEDAD CIENTIFICA 


The formations encountered along the line of section are not com- 
plex. The measurements both horizontal and vertical have been care- 
fully taken and the work will serve as a basis for further investiga- 
tion. 
The following will serve as a guide. All of the formations here ta- 
bulated are not found in the above section, but are met with elsewhe- 
re and in the inmediate vicinity. 
Conglomerate, sandstone and shale to the 
Pliodone | south west of Churunuco. 
Khyolite. 
ica of the lower Balsas Valley. 
Tertiary Breccia of the Balsas Valley at San Miguel, 
Ajuchitlan and Coyuca, etc. 
Andecite porphyry. 
Diorite. 
Limestone Conglomerate at Tonalapa del 
¿ Rio and Malpaso. 
Washita Division—Escamela limestone. 
| Frida Division—Maltrata limesto- 
ne. 
Cretaceous Trinity Division * Necoxtla Slates. 7 
Gr Slates and s. s. Huetamo section , € 
Neocomian Coyuca limestone with Nerinea titanea 
(Felix): 
Miocene 
o 
Eocene 
Comanche 
series 
Crystaline slates.—Placeres, State of Guerrero.—Triunfo, Lower Ca-: 
lifornia, etc. 
Grey granites and syenites. W. of Coyuca, Guerrero: —Cacachilas, — 
Lower California, etc. 
But little explanation is necessary as the various formations are Ca- 
refully indicated on the section. 
Passing the alluvial valley of Iguala, the first rock met with is an 
outlying synclinal of heavy bedded limestone of the Escamela group, 
1 The Trinity, Fredericksburg, Washita classification is taken from “Boletin 
del Instituto Geológico de México.” Geología de los Rededores de Orizaba por 
Emilio Búse, 1899—p. 16, and the other divisions haye been conected with the 
classification of Ur. Aguilera, Director of Instituto Geológico. 
