404 STUART WELLER 



In southeastern Randolph, and in Jackson County to the valley 

 of the Big Muddy River, the Degonia is a conspicuous cliflf-forming 

 sandstone, well exposed in the Mississippi River bluffs and in 

 some of the tributaries to the Mississippi. In its massiveness the 

 formation is perhaps more nearly comparable with the Cypress 

 sandstone of the southern counties than with any other Chester 

 sandstone, and where it is best exhibited it is commonly exposed 

 in vertical cliffs forty or fifty feet in height, although the total 

 thickness of the formation is considerably greater than this. The 

 sandstone is somewhat coarser than most if not all of the other 

 Chester sandstones, and is so much like some of the lower Potts- 

 ville beds of the adjoining regions, in localities where such beds 

 are free from pebbles, that it is impossible, in places where the 

 Kinkaid limestone is wanting, to always establish the line separat- 

 ing the Degonia from the Pottsville. Indeed this whole sand- 

 stone formation was considered to be Pottsville by Shaw, and was so 

 mapped in the Murphysboro Quadrangle.^ 



In some sections, and perhaps in all, the whole of the Degonia 

 is not as massive as the conspicuous cliff-making beds of the for- 

 mation, but consists of thinly bedded or almost shaly sandstone in 

 which the individual beds are undulating or curling, the undulations 

 being irregular in character and having a width of only a few 

 inches and a height of an inch or two. In places the more massive 

 layers and the thinly bedded layers are arranged alternately in 

 the sections, the units being variable in thickness up to fifteen or 

 twenty feet. The total thickness of the Degonia sandstone 

 throughout its extent in Randolph and Jackson counties varies 

 only slightly from one hundred feet except where it is the highest 

 formation in the Chester series and has been subjected to pre- 

 Pennsylvanian erosion. 



Of all the Chester formations the Degonia sandstone is most 

 nearly continuous from the Mississippi River counties into the 

 more southern area of the state, and further field studies may 

 establish the complete continuity of the formation from one area 

 into the other. In Jackson County the formation has been traced 

 southward to the valley of the Big Muddy River. It is 



^ Geologic Atlas of U.S., Folio No. 185 (1912), p. 6. 



