The Andes of southern Peru . EvS Alluvium ^^limestonelHIDSandstone 5 Shale ^Volcanic CEETACEOtJS The Cretaceous formations are of very limited extent in thebelt of country under consideration, in spite of their generallywide distribution in Peru. Theyare exposed distinctly only onthe western border of the Cor-dillera and in special the gorge of Cotahuasi, overseven thousand feet deep, abouttwo thousand feet of Cretaceouslimestones are exposed. Theseries includes only a very re-sistant blue limestone and ter-minates abruptly along a well-marked and highly irregnilarerosion surface
The Andes of southern Peru . EvS Alluvium ^^limestonelHIDSandstone 5 Shale ^Volcanic CEETACEOtJS The Cretaceous formations are of very limited extent in thebelt of country under consideration, in spite of their generallywide distribution in Peru. Theyare exposed distinctly only onthe western border of the Cor-dillera and in special the gorge of Cotahuasi, overseven thousand feet deep, abouttwo thousand feet of Cretaceouslimestones are exposed. Theseries includes only a very re-sistant blue limestone and ter-minates abruptly along a well-marked and highly irregnilarerosion surface covered by al-most a mile of volcanic ma-terial, chiefly lava flows. Thecharacter of the bottom of thesection is likemse unknown,since it lies apparently far be-low the present level of ero-sion. The Cretaceous limestones of the Cotahuasi Canyon are every-where greatly and irregularly disturbed. Typical conditions arerepresented in the maps and sections. Figs. 166 and 167. They are. Fig. 166—Geologic sketch map andcross-section in the Cotahuasi Canyon atCotahuasi. With a slight gap this figurecontinues Fig. 167 to the left. The sec-tion represents a spur of the irain plateauabout 1,500 feet high in the center of tliemap. 218 THE ANDES OF SOUTHERN PERU
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Keywords: ., bookcentury1900, bookdecade1910, bookidandeso, booksubjectgeology
