NO. 7 



EARLY CENOZOIC VERTEBRATES — FRIES ET AL. 



lowest part visible consists largely of layers of andesitic and basaltic 

 tuff, breccia, and lava, interbedded with tuffaceous sandstone of dif- 

 ferent colors {Teoc in fig. 2). These beds grade upward into beds 

 of sandstone, siltstone, and fine-grained conglomerate (also Teoc) 



EXPLAMATION 



/ LOcl 



(_ Alluvium 



Coarse, uncon;olidoled conglomerate 



I r [1^7] 



•2 1 Rhyolilic and ondesitic volconic rocks, 

 j thin tuffaceous sondslone al boss 



g,| Coarse red conglomerote 



5| iTeoc I 



^ I Red conglomerate and sandsione;vari-colored 

 g < ondesitic ond bosoltic volcanic rocks in lower 

 ,3 •» [part, probobly not older than late Eocene 



i [^m 



2 JMetomorphosed sedimentary ond intrusive 

 S I rocks, includes rocks of probable Jurassic 

 f ond Triossic oge 



Geologic contact; ddshed Met 

 where opproximotely located zoneb 

 direct 



Fault, showing direction of 

 dip, doshed where inferred 



Approximate scoie 



Fig. 2. — Geologic map of red-conglomerate outcrop area at Guanajuato, showing 

 vertebrate fossil locality. 



of a predominantly reddish hue. A disconformity separates these 

 beds from overlying coarser grained conglomerates (Toe), which 

 are also dominantly reddish. 



Nearly two-thirds of the pebble-size or larger constituents of the 

 conglomerate consist of fragments of volcanic rocks, mainly rhyolite 



