16 UNIVERSITY OF MISSOURI STUDIES 



The great preponderance of carbonate rocks indicates that 

 the formations were offshore deposits. The considerable amount 

 of sandstone found in the upper formations points to a shifting 

 of the shore line, so that at times the area was nearer to the shore 

 than it was at other times. 



STRATIGRAPHY 



Elvins formation 



The Elvins formation has a limited distribution in the area. 

 In nearly every case its exposures are due to structural changes. 

 The various outcrops are in the extreme southeastern corner of 

 the area; a small section on the eastern boundary; a rather large 

 section along Big River and Mineral Fork in T, 39 N., R. 3 E. ; 

 and the region along the two forks of Calico Creek. In most of 

 the places where the formation outcrops its position is due to 

 faulting and folding. 



There are good exposures of parts of the formation along 

 the larger streams. The bluffs of Big River, near where it is 

 joined by Mineral Fork, afford excellent exposures. The out- 

 crop in the extreme southeastern corner is along Big River also, 

 and furnishes a fair exposure, altho the major part of the bluff 

 is covered with talus. The members of the lower part of the 

 Elvins formation are well exposed along Blays Creek after it 

 crosses the fault that brings these beds up alongside the younger 

 members. There are fairly good exposures along Mineral Fork 

 and for a short distance up Old Mines Creek. Nowhere is the 

 complete section shown. Two partial sections were made, of 

 which one is given below. The thickness of the formation is 139 

 feet 9 inches on the bluff of Big River and 135 feet on Fertile 

 Creek. 



Wherever the Elvins formation is found, the slopes are 

 rocky and only thinly covered with soil or mantle rock. The for- 

 mation is exposed as cliffs along the larger streams. Cedars 

 predominate on all outcrops of this formation'. It is rather strik- 

 ing to see them on one side of a fault plane with oaks on the other 

 side at the same elevation. 



Petrography of the formation. — In composition the Elvins 

 formation is one of the most variable formations of the region. 



