Red beds of southwestern Colorado and their correlation*

The strata of reddish color, in varying tints and shades, often referred to as the “Red beds,” constitute one of the most striking terranes in the sedimentary section of the Rocky Mountain province. Consisting in the main of sandstones and conglomerates, beds of other character, such as shale, limestone, gypsum, etcetera, are more or less prominent in many localities. While the complex in question is one of wide distribution and has been examined and described by many geologists, it is still very imperfectly known as to its age and the correlation of the sections of different areas. The rarity or absence of fossils, the varying vertical extent of the red color, and the common lack of stratigraphic evidence suggesting division planes combine to make a satisfactory analysis of the Red beds difficult.

Where the complex in question has what may be . . .