12 STUDIES IN GEOLOGY, No. 4 



There was not time for a detailed study of the Carbon- 

 iferous of Paracas since the peninsula is a practically unin- 

 habited desert. The wide and desert coastal plain, inter- 

 rupted only by the irrigated valley of lea, that extends from 

 the igneous foothills of the Western Range to the ocean, 

 consists of wind blown sands, desert pavement gravel and 

 paper shales. Similar deposits form the neck of the Paracas 

 peninsula, which is thus the result of the block faulted Car- 

 boniferous and apparently bears no relation to westerly spurs 

 from the Andes or igneous intrusions in the Coastal Plain. 



Following is a measured section of the easternmost fault 

 block and was repeated in the next block to the southwest. 

 The horizons from which fossil plants were collected are 

 indicated and there is no chronologic change in the flora 

 from top to bottom although fossil plants are more varied 

 in the lowermost horizon. 7 



FEET 



Thin to heavy bedded rather coarse greenish-gray sandstone. ... 13 

 Greenish-gray massive and cross-bedded sandstone with varying 



amounts of shaly intercalations with Lepidodendron. (N. 21 



E,26E) 75 



Dark shale with sandstone layers less than a foot in thickness. . 55 



Sandstone with a shale parting in the middle 35 



Sandy and somewhat carbonaceous fossiliferous shale 80 



Sandy shale (tunnel) 22 



Massive sandstone passing into thin-bedded sandstone along the 



strike. (N. 9 E, 25 E) 30 



Massive greenish-gray somewhat arkosic sandstone 15 



Thin-bedded sandstone 10 



Thin-bedded sandstone with dark shale (no coal) toward the 



top (tunnel in shale) 3 2 



Alternating sandy and carbonaceous shale with 6 inch coal at 



top, abundantly fossiliferous (tunnel) 38 



Massive greenish-gray somewhat arkosic sandstone 20 



Shale carbonaceous above, sandy below (N. 20 E, 25 E) (tunnel) 10 



Greenish-gray sandstone, thin-bedded above. 5 



Gray shale 2 



Interbedded thin sandstones and shales 3 



7 Section measured by Dr. Joseph T. Singewald, Jr. 



