A DEVONIAN OUTLIER NEAR THE CREST OF 

 THE OZARK UPLIFT 



JOSIAH BRIDGE and B. E. CHARLES 

 Missouri School of Mines, RoUa, Missouri 



INTRODUCTION 



The Paleozoic history of the Ozark UpHft constitutes an 

 extremely interesting stratigraphic study, and one upon which 

 comparatively little has been written. The earher stages of this 

 history, up to the close of the Canadian epoch, are fairly well 

 known, for rocks belonging to this and the preceding epochs are 

 well exposed throughout the uplift. Of the later history but Httle 

 is known, for so thoroughly have the subsequent periods of erosion 

 performed their work, that only small and widely separated outliers 

 of the younger formations remain on the higher parts of the upHf t. 

 Around the borders of this dome are belts of younger formations, 

 more or less completely encircHng it, and it has always been a 

 question as to how far these formations once extended toward the 

 crest of the structure and which of them, if any, completely covered 

 it. Upon this question no two sets of paleogeographic maps agree. 

 One of the chief reasons for this disagreement is lack of information 

 concerning the region, for, as a whole, there has been Httle detailed 

 stratigraphic work done in the region of the Ozark Uplift. 



In the area around Rolla (no miles southwest of St. Louis and 

 well toward the crest of the uplift) the existence of outHers of 

 Pennsylvanian and Mississippian age has long been known. The 

 former consist of stratified deposits of sandstone and shale, and 

 cover far greater areas than are shown on existing maps.^ The 

 Mississippian outliers are, for the most part, small areas covered 

 with fossihferous, residual bowlders,^ which have apparently weath- 



' The new geological map of Missouri, now in press, shows many of the larger 

 Pennsylvanian outliers. 



'^ Josiah Bridge, "A Study of the Faunas of the Residual Mississippian of Phelps 

 County (Central Ozark Region), Missouri," Jour. Geol., Vol. XXV (1917), pp. 558-75. 



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