CHIAPAS, TABASCO, AND PENINSULA OF YUCATAN 939 



while on the contrary those in Chiapas are generally much 

 inclined and fractured. 



A. SEDIMENTARY FORMATIONS. 



I. Azoic for)natwns. — In addition to some very limited bands 

 of gneiss, mica-slate, and phyllites surrounded with granite, 

 which I observed in 1893 in the Sierra Madre, in 1894 I came 



Geology 



of 



YUCATAN 



across in the first northern range of the same Sierra, near the 

 plantations of "Piedad" and "San Vicente," another band of 

 crystallines trending N. 7° W. and dipping 5° to the N. E. 

 Among bowlders washed down by the Aguacate River one can 

 see gneiss, mica-slate, and phyllites, which indicate the presence 

 of these formations m these regions and in the interior of the 

 Sierra Madre. 



On account of the total absence of means of communication 

 in the Sierra mentioned, entrance to the interior, now practically 

 unknown, is almost impossible ; hence on the geological 

 maj:) I have not been able to indicate the occurrence of the 

 Azoic formations except in a very general way. 



2. Strata of Santa Rosa. — As I said in a preliminary report in 

 1893, I have adopted this term of the French geologists, A. 



