130 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Se«. 



of the fossils, and states that they lie in front of the Tam- 

 asopa limestone outcrop here and to the south. He makes 

 no mention either of Valles or Mendez in this area. 



Huntley's map shows the Tanlajas beds as upper Tertiary 

 and separated from the Tamasopa limestones lying west of 

 them by belts of Mendez and San Felipe deposits as far 

 southward as the map extends. 



Jeffreys says his San Felipe beds are transition beds be- 

 tween the underlying Tamasopa limestone and the overlying 

 Mendez shales. Limestones predominate toward the base 

 giving place to blue shales toward the top. He estimates 

 their thickness at not more than 500 feet. It is the equiva- 

 lent of our San Juan. 



Huntley describes his San Felipe formation as follows : 



"This may be described as a transition series between the 

 upper Mendez marls and shales and the underlying massive 

 Tamasopa limestone. It begins with an occasional thin lime- 

 stone shell. These increase with depth in number and thick- 

 ness, being interbedded with blue shales which conversely de- 

 crease in thickness downward until the series gives place to 

 massive limestone. These beds apparently vary in thickness 

 from about 300 to as much as 800 feet." 



It corresponds approximately to our San Juan, and on his 

 map is confined to the eastern face of the Boca del Abra 

 Mountains, the valley west of them, and a belt along the face 

 of the main range. 



The Mendez of Jeffreys, named from the Mendez east of 

 Ebano, and which includes the Papagallos and probably some 

 part of the Tertiary, is thus described : 



"This formation consists of a very uniform deposit of gray 

 to blue shales, which, in the higher levels, verge into an in- 

 durated clay or semi-marl, with a bolder fracture instead 



of the fine shaly appearance From top to bottom 



of this Mendez marl there is practically no change in the 

 lithological character, save some irregular beds, varying from 

 two inches to two feet thick, of a sandy limestone." 



The Mendez of Huntley is the same as that of Jeffreys, 

 but he refers it as a whole to the Eocene. He says of it : 



