398 STUART WELLER 



counties. Further field studies may serve to prove or disprove 

 this suggestion. 



W alter sburg sandstone. — On Bay Creek, between Simpson and 

 Grantsburg, near the line separating Pope and Johnson counties, 

 there is a conspicuous sandstone formation overlying the Vienna 

 limestone. The maximum thickness of this sandstone along Bay 

 Creek is about sixty or seventy feet, but it is reduced in thickness 

 both to the east and to the west. In an easterly direction the sand- 

 stone has been recognized at its proper position in the section 

 nearly to Grand Pierre Creek in eastern Pope County. To the 

 west it is known to extend, but much reduced in thickness, nearly 

 to the Johnson-Union County line, and it may be found to continue 

 into Union County. As viewed along an east-west section across 

 the southern counties of Illinois, this formation is a lenticular body 

 of sandstone with a lateral extent of nearly forty miles. The 

 extent of the formation in a north-south direction is not known. 



The importance of this unit in the Chester section was first 

 recognized in Pope County, northwest of Golconda, where it is 

 well exposed in the road just north of Waltersburg, from which 

 locality the formation has been named, although it is by no means 

 as thick at this point as it is farther west. In its area of maximum 

 development the Waltersburg is a massive, cHff-forming sandstone, 

 not conspicuously different in character or appearance from por- 

 tions of the Bethel, Cypress, Hardinsburg, or Tar Springs sand- 

 stones. Wh^e the formation approaches its lateral limits to the 

 east and west, it is a thinly bedded, rather impure sandstone, in 

 layers two or three inches thick, which are commonly distinctly 

 jointed in two directions, one set of joints being placed at intervals 

 of two or three inches, the other at a foot or more. These two 

 systems of joints cause the rock layers to break up into elongate, 

 splinter-like blocks which are rather characteristic. There are 

 places where the entire formation is represented only by two or 

 three feet of sandstone of this character, situated between the 

 black shale of the Vienna below and the calcareous shales and 

 limestones of the Menard above. 



No fossils have actually been observed in the Waltersburg, 

 but trunks of Lepidodendron, such as are found in the other Chester 

 sandstones, may be expected. 



I 



