MISSISSIPPIAN OF PHELPS COUNTY, MISSOURI 561 



erosion of the Pennsylvanian, but there is also the possibility that 

 these deposits were in the bowlder form before the invasion of the 

 Pennsylvanian seas. In either case the character of the bowlders 

 seems to indicate that they have not been moved far from their 

 place of origin, if they have been moved at all. 



Lithologically the bowlders fall into a number of well-marked 

 groups. The more abundant ones are of course, dense, quartzitic 

 sandstone, which in its original state was probably a calcareous 

 sandstone. In their present condition the calcium carbonate 

 content has been completely removed by leaching, and thin sec- 

 tions show them to be made up entirely of clear quartz grains 

 exhibiting little evidence of secondary growth. The interior of 

 these bowlders is semi-translucent, bluish white in color, and the 

 rock is quite hard and dense, but the more weathered, external 

 portions are extremely porous and deeply stained with iron oxide. 

 They are abundantly fossiliferous, but the fossils are scattered 

 irregularly through the rock with no arrangement that would 

 suggest bedding. Associated with the quartzitic bowlders are 

 masses of soft, friable, fine-grained white sandstone, which are 

 somewhat leached and in which the more weathered phases are 

 deeply stained with iron oxide. Otherwise the rock is but little 

 altered. The fossils of these sandstone masses are arranged in 

 parallel bands, which probably correspond tb the bedding planes 

 of the formation. 



Bowlders of chert are also abundant. Some are practically 

 unweathered, others are so completely leached that they powder 

 under the hammer. For the most part they are white or pale 

 bluish white in color, and, like the sandstone bowlders, they are 

 stained with iron oxide in proportion to the amount of weathering 

 which they have undergone. At one locality a single chert bowlder 

 has been found which is of a pale pink color, the color appearing 

 to be original. 



Lee 1 has mentioned that bowlders of siliceous oolite of Mississip- 

 pian age occur at one locality associated with bowlders of the 

 quartzitic type. A careful examination of such oolite bowlders 

 from this and other localities where they are associated with residual 



1 Ibid., p. 42. 



