242 
STRATIGRAPHICAL GEOLOGY 
Miraflores, about 5 miles down the valley from El Molino, a 
sandy limestone at approximately the same horizon, contains a lim¬ 
ited marine fauna. Steinmann’s collections from the former lo¬ 
cality contain, according to Fritzsche, Pseudodiadema rotulare, 
Desor, Holectypiis sp?, Lima cf. galloprovincialis, Matheron, and 
Nerinea sp? i.The most abundant form in our collection from 
Miraflores is the form that Fritzsche calls Pseudodiadema rotulare, 
Desor. We have about one hundred individuals of this form 
and these are identical in the structure of their ambulacral plates, 
the crowding of the pores near the peristomial margin, the solid 
spines, and imperforate primary tubercles, with a species of 
Cyphosoma common in the Late Cretacic rocks of Peru where it 
is associated with a varied and typical fauna. It would be singu¬ 
lar that we should have collected from a limited outcrop, scores 
of Cyphosoma, whereas Steinmann collected only Pseudodiadema. 
The genera are superficially similar and the conclusion seems 
warranted that both names refer to the same Echinoid. More¬ 
over they are associated with sparse remains of a Pecten close to 
the so-called P. quinquecostata. 
This fixes the age of this part of the Puca Sandstone as Late 
Cretacic and not Barremian age, and leads to the suggestion that 
the gypsiferous, lagoonal red-beds, or Puca Sandstone, instead of 
being of the same age as the littoral and continental coal-bearing 
Cretacic deposits of Peru, is really contemporaneous with the 
maximum extension of the Late Cretacic sea in the region occu¬ 
pied by the Andean geosyncline, and represents the shoreward 
deposits along the eastern margin of the geosyncline over an area 
500 to 600 miles in length, lying east of the present divide of the 
Eastern Andes, which were contemporaneous with the Late Cre¬ 
tacic limestones represented from southern Peru northward to 
Colombia, and southward in Chile and Patagonia. 
The exact stage in the Late Cretacic Period of this maximum 
expanse of the Late Cretacic sea is not yet definitely determined, 
nor does it seem possible to reach final conclusion with the present 
knowledge of the faunas; it may be early as the Cenomanian or 
as late as the Emscherian, but it is certainly not either earlier or 
later. 
Berry. 
