58 H. E. Gregory — A Geologic Reconnaissance 



beds contain gypsum in small amounts, and thin lenses and 

 seams of gypsum were observed at several localities. Strati- 

 graphically below the strata included in Section I elongated 

 lenses of limestone conglomerate and of limestone 3 inches to 

 4 feet in thickness become more abundant; and at the head of 

 the tributaries to Rio Qquilque bands of limestone, limestone 

 conglomerate, and gypsum are widely displayed. In places 

 these rocks are represented by masses of white paste. 



In the valley of the Rio Ayahuaycco the more calcareous 

 portion of the Qquilque formation is represented in a section 

 which contains the following strata : 



II. Section of calcareous portion of Qquilque formation in 

 a branch of Ayahuaycco Quebrada, about half a mile above 

 its junction with Rio Qquilque. 



Top. Feet. 



1. Shale, dark red, calcareous; with gypsum in seams and 



beds 30 



2. Limestone conglomerate, composed of concretionary pel- 



lets, size of bird-shot . 0.3 



3. Limestone, calcareous or massive shale, brown, mottled 



with patches and bands of yellow; concretionary . . 6 



4. Sandstone, yellow, highly calcareous, with shale part- 



ings 2 



5. Limestone conglomerate, pellets from size of bird-shot 



to size of buckshot 2 



6. Sandstone, banded green, yellow, and brown; thin- 



bedded 4 



7. Shale, banded, and copper-green limestone; shale gypsi- 



ferous 12 



8. Limestone, arenaceous, red-brown, in general massive, 



but full of gray limestone concretions; bands of 

 gypsum and lenses of limestone conglomerate. This 

 bed may not be in place 30 



86.3 



The strata in this section have been disarranged by a number 

 of small faults. 



The nature of the rocks and the order of deposition indicated 

 by Sections I and II are fairly typical for the entire Qquilque 

 formation. In places, however, as at the head of the Huat- 

 anay, lenses of limestone conglomerate, separated only by thin 

 layers of brown or gray sandstone, highly calcareous shale, or 

 gray-blue massive limestone, are particularly abundant. In the 

 bed of the Huatanay south of Sacsahuaman is a bed of con- 



