1 68 C. W. TOM LIN SON 



below the surface the rocks are no longer red. S. F. Emmons states, 

 respecting the Maroon formation of the Tenmile district, Colorado, 1 

 that "in depth, as shown in underground workings, the red color 

 generally gives way to a greenish gray." In another paragraph of 

 the same folio, Emmons states that igneous or hot-water alteration 

 destroys the red color. Inasmuch as the ores of this district are 

 related intimately to igneous and hot-water action, it is natural 

 to suppose that mine workings would be the most likely of all 

 places in which to find such effects. The relation here described 

 is probably a local and abnormal phenomenon. 



In his description of the sedimentary rocks of the Anthracite 

 and Crested Butte quadrangles, where the general situation is 

 similar to that in the near-by Tenmile district, Eldridge 2 states that 

 "the upper division [of the Maroon conglomerate] is of a peculiar 

 red or chocolate color, except in regions of local metamorphism " 

 of the kind mentioned also by Emmons. 



Drilling explorations in the oil regions of Oklahoma and Texas 

 recently have given us some additional information on the behavior 

 of the color with depth. Gould 3 tells of a well some 3,300 feet deep 

 in southeastern Oklahoma, in which "the last of the typical Red 

 Beds was encountered" at a depth greater than 2,000 feet. The 

 underlying strata were dull-colored sediments like those outcropping 

 along the eastern (lower) margin of the Red Beds. Nowhere does 

 he mention any change in color due to depth. 



A well sunk 3,095 feet at Ashland, Wisconsin, passed through 

 typical red sandstones of the Lake Superior group all the way, 

 without any suggestion of a change in color with depth. 4 



It is to be remembered that most of the western Red Beds 

 series are not colored uniformly throughout, but include many 

 lighter-colored strata; and that many of the Red Beds successions 

 include gray and green members. Any drill cutting through such 

 a series would find, of course, changes in color with depth, but they 

 would not be progressive, and they would have no causal connection 

 with depth whatsoever. 



x Op. cit. 2 Op. cit. 



3 C. N. Gould, "Petroleum in the Red Beds," Economic Geology, VIII (1913), 

 768-80. 



4 Data from F. T. Thwaites, op. cit. 



