COLORADO PLATEAU 



417 



contiguous strata, but at other times and places the saline beds have be- 

 haved independently and, through plastic flow and solution, have pro- 

 duced large-scale structures in the overlying beds that have no expression 

 in the underlying strata. 

 Taking the Gypsum Valley anticline as an example, Stokes ( 1948 ) re- 



5T A GE I 



jTAGE 2 



stage: 3 



5 TA6E A 



Fig. 26.12. Sketch map of eastern Utah and western Colorado showing principal structures due 

 to salt flowage and solution. Reproduced from Stokes, 1948. 



Fig. 26.13. Development of the salt anticlines in the Colorado plateau. Reproduced from Stokes, 

 1948. Vertical scale exaggerated. C, Hermosa formation; P, Permian formations; \, Triassic 

 formations; Jgc, Glen Canyon group; Jsr, San Rafael group; Jm-Kd, Morrison to Dakota forma- 

 tions; Km, Mancos shale; Kmv, Mesaverde group. 



cords the following development (see series of cross sections in Fig. 26.13). 



1. Deposition of salt and gypsum in Paradox formation of late Penn- 

 sylvanian age. Deposition of covering Hermosa limestone beds. 



2. At end of Pennsylvanian or in early Permian time, the salt pushed 

 upward and domed the Hermosa; the Hermosa was eroded and the 

 salt exposed. 



3. The late Permian Rico and Cutler formations were deposited around 

 the dome or anticline. 



4. The salt dome was eroded nearly to a peneplain by late Triassic, and 

 the Triassic and early Jurassic formations overlapped across the edges 

 of older formations around the dome. 



5. The late Jurassic sediments practically submerged the salt mass, and 

 then the late Cretoceous formations were deposited undisturbed o\ er 

 the site of the salt mass. These five steps are all recorded in the first 

 cross section of Fig. 26.13. 



