i 5 4 C. W. TOM LIN SON 



PART II 



Conditions of Deposition of Red Clastic Sediments: Modern Types 

 Red Clay of the Deep-Sea Bottom 

 Stream Deposits Derived from Pre-existing Red Beds 

 Arkosic Stream Deposits 

 Stream Deposits Deriving Their Coloring Matter from Ferruginous 



Residual Soils 

 Terrigenous Marine Clastics 

 Deposits of Desert Lakes or Playas 

 Red Dune Sands 



Evidence of Features Other than Color as to the Conditions under 

 Which the Red Beds Were Deposited 

 Evidence of Conglomerates as to the Sites of Land-Masses 

 Significance of Non-clastic Sediments 

 The Clastics: Minor Structural Features 

 The Clastics: Mineral Composition 

 Evidence Supplied by Fossils 

 Summary 



Relation of Orogenic History to Red Beds Sedimentation 



Summary 



PART I 



PREFACE 



Certain general facts concerning the origin of the western Red 

 Beds have been known for some time and have become incorpo- 

 rated into current textbooks. There has been, however, much 

 difference of opinion in the interpretation of some features of this 

 remarkable group of sediments, especially as to the significance of 

 the color itself. This paper is devoted to an investigation of the 

 causes and history of the coloring matter, which, more than all 

 other features put together, distinguishes the Red Beds from other 

 sedimentary series. 



The investigation on which this paper is based* has been chiefly 

 a study of the literature to which reference is made in the footnotes, 

 together with all available published descriptions of the western 

 Red Beds, and much miscellaneous literature dealing with related 

 subjects. The writer's first-hand acquaintance with the Red 

 Beds has been gained from two summers of field work in Wyoming 

 and Idaho (under the direction of Eliot Blackwelder, of the United 



