CARBONIFEROUS FORMATIONS OF THE OZARK UPLIFT 339 



tion doubtless formed a deep residual soil, partially from the insoluble 

 residue of the Burlington Hmestone, but largely from that of the 

 Cambro-Silurian dolomites and sandstones. 



8. Abundant plant and animal life. — Plants and animals are 

 important, in producing, directly or indirectly, carbon dioxide. The 

 tropical or subtropical climate, the humidity, and the abundant car- 

 bon dioxide favored abundant plant life. 



The chief underground circulation must have been to the north 

 and northwest to the Coal-Measure sea, following the present and 

 doubtless the former dip of the strata. Judging from the pre-Coal- 

 Measure sink-holes, the water level must have been from 40 to 125 

 feet below the pre-Coal-Measure surface. The surface circulation 

 was probably bounded below by the intercalated shales of the Cambro- 

 Silurian formations. At the beginning of pre-Coal-Measure erosion 

 the surface circulation may have been but 150-250 feet deep. 



Because of the ready solubility of the Burhngton limestone and, 

 perhaps, of initial depressions in the upper surface of this formation 

 along pre-Burhngton drainage lines, arising from the unequal thick- 

 ness of the Burhngton cover, erosion tended to exhume the old 

 valleys. They may be referred to as "resurrected valleys" — a term 

 kindred to "resurrected mountains" (Davis). 



Deposition 0} the Saline Creek cave-conglomerate. — The oldest 

 formation of the Pennsylvanian, the Saline Creek cave-conglomerate, 

 hes in joints, enlarged by solution, in sink-holes, and in cave-galleries 

 in the Burlington and Cambro-Silurian limestones and dolomites. 

 At the exposure on Tavern Creek the formation is at least 60 feet 

 deep and includes blocks 18 feet long. The Cambro-Silurian lime- 

 stone dips toward the sink for 150 feet on either side. A cistern at 

 Mr. Ramsey's follows a joint filled with Sahne Creek cave-conglom- 

 erate 18 feet into a filled cave-gallery 11 feet across. The bowlders 

 of the Sahne Creek cave-conglomerate are noticeably local in origin, 

 and are not only too large to have been transported by any streams 

 possible with the supposed topography, but many of them are of 

 such soft material that they could not have been carried far. The 

 composition of the shales corresponds in a general way in lime and 

 sand content with that of the surrounding rocks. 



In consequence, it is inferred that these solution cavities were 



