of the Cuzco Valley, Peru. 57 



Feet. 



42. Sandstone, brown, very fine, minutely cross-bedded; 



calcareous cement; vertical tubes like worm boles; 

 carbonaceous patches; surface sun-baked and with 

 imperfect mud cracks; mud lumps and tiny lime 



concretions on surface 0.5 



43. Shale, chocolate; sun-dried surfaces; flakes of mus- 



covite 5 



44. Sandstone, brown 1 



45. Shale, chocolate 3 



46. Sandstone, brown 7 



47. Shale, chocolate 2 



48. Sandstone, brown 1 



49. Shale, chocolate 1.5 



50. Sandstone, brown 1 



51. Shale, chocolate 2 



52. Sandstone, brown and gray bands 3 



53. Shale, chocolate 6 



54. Sandstone, brown, with 1-foot layer of gray sandstone 



at top 9 



55. Shale, chocolate 1 



56. Sandstone, brown 1 



57. Shale, chocolate 12 



58. Sandstone, brown 4 



59. Shale, chocolate 10 



60. Sandstone, brown 4 



61. Shale, chocolate, with thin bands of sandstone 14 



62. Sandstone, brown ; sun-baked surfaces and ripple marks 1 



63. Sandstone, gray 1 



64. Sandstone, brown, interbedded with chocolate shale . . 50 



65. Interval (estimated) 100 



66. Limestone conglomerate, gray to blue-gray; chiefly 



concretionary pebbles and irregular fragments of 

 limestone, the size of small shot to half an inch in 

 diameter; a few chert pebbles; bed lenticular; top 



not exposed 4 



67. Sandstone, gray to yellow-green; medium-grained 



quartz; thin-bedded, cross-bedded; includes thin 



sheets of finely laminated shale 15 



546 



Most of the beds in Section I do not retain their individual- 

 ity for more than a few hundred feet ; overlapping lenses rather 

 than widely extended layers of uniform thickness constitute 

 the bedrock, and the strata themselves, in many places, are 

 made up of thin imbricated sheets of small areal extent. Many 



