PALEONTOLOGY ZORRITOS FORMATION 9 



ic allocation of the plant horizon on the locality, which was 

 given by the collector as 20 miles south of Tumbes, and 200 

 to 300 feet from the ocean. This is undoubtedly the locality 

 north of Caleta Grau described by Grzybowski, the bed of 

 lignite there being the only one known in any of the forma- 

 tions occurring in the neighborhood, and the location other- 

 wise agreeing with the account given by Mr. Winslo-w. It 

 should be noted that the evidence of the plants bears upon 

 the upper Variegated formation instead of the Heath, as 

 stated by Professor Berry in accordance with Grzybowski's 

 determination of the beds. 



That point clear, discussion of the section as recently 

 determined may be continued from the point at which it was 

 left. The Upper Zorritos formation consists at the top of a 

 yellowish concretionary sandstone, called by van Hoist 

 and Singewald the "cannonball" sandstone on account of 

 the characteristic weathering out of the concretions in cliffs. 

 This peculiarity of the sandstone suggested the name of 

 Piedras Redondas, at which place it occurs prominently in 

 the headlands, and at some points it forms cliffs whose 

 erosion form is recognizable for miles. The "cannonball" 

 sandstone underlies the Talara beds at Piedras Redondas. 

 Underlying the "cannonball" is a series of massive beds, in 

 part heavy conglomerates, and in part sandstones which are 

 locally calcareous, bearing fossils and often petrified wood. 

 Yellow is the prevailing color. The Upper Zorritos mol- 

 luscs later discussed in detail were obtained from these 

 beds. The base of this series consists of very friable sand- 

 stones which weather into a yellow sand. 



Directly underlying the yellow friable sandstones are the 

 beds d i of Grzybowski, which form the upper part of the 

 Variegated formation. The highest of these are green clays, 

 locally red, gray, and purplish, the varicolored assemblage of 

 which suggested the name of the formation. Below these 

 clays are the carbonaceous Heath-like shales, oyster beds 



