“ANTONIO ALZATE.” 329 

which is followed by the thinly bedded limestones of the Maltrata 
group. which extend as far as Guajiote (K 9.3). 
These limestones apparently extend to the base of the Campana 
mountain, which is formed of the Escamela limestone and is indicated 
in the section in the back ground. 
From Guajiote the slates (Necoxtla group) extend to the base of the 
Cocula mountain, which is west of Tonelapa del Rio. (K 13). 
The Cocula or Cuatepec mountain is formed by the Escamela limes- 
tone and may be considered as a synclinal mountain, although in ts 
ces it is formed by a series of folds. 
On the east, as well as the west side of this mountain the slates 
appear and the limestone can be seen resting upon the upturned and 
eroded edges of the Necoxtla slates. 
The thinly bedded limestones of the Maltrata group are met with a 
short distance west of the margin of the heavy bedded limestones of 
the Escamela group and are folded and countorted with the slates 
(Necoxtla). The slates are capped by the limestones (Escamela) which 
occurs in small synclinal basins, and over small areas and even in ic- 
elated blocks as far as Teloloapan, ' where both the slates and the li- 
mestones are cut off by an extensive diorite dyke. 
The inmediate serroundings of Teloloapan are exceedingly broken 
owing to the geological condition described. 
The dyke extends to the Sayulapa river and reaches to a considera- 
ble distance to the North east and south west. 
Passing the Sayulapa river the thinly bedded limestones (Maltrata 
group) extend to the vicinity of Zacatlancillo (K. 56). I am not able to 
determine the structure and have indicated transverse faults, which 
may account for the lateral extent of the formation. 
The slates (Necoxtla group) extend from Zacatlancillo to the Mar- 
gin of the Balsas river valley, being traversed by rhyólite dykes in pla- 
ces and capped by the thinly bedded limestones (Maltrata) im various 
places, as indicated in the section. 
1 The name feloloapan is Nahbuatl or Aztec and signiñes Río del Pedregal 
«he river of the rocks.” 
