Bulletin 12 134 



Riverside Sandstone and New Providence Shale. 



The series of sandstone and shales known in the Indiana and 

 Kentucky Reports as the "Knobstones' ' may be separated into two 

 divisions which are lithologically decidedly unlike in most sec- 

 tions. The uppermost of these divisions consists usually of mas- 

 sive sandstones and sandy shales. Below the sandy shales and 

 sandstones a blue clay shale is found resting either on the Black 

 shale or the Rockfprd limestone. The name "New Providence 

 shale" was used locally for this division of the "Knobstone" in 

 1873 by Mr. Borden. He used it to designate the lower Knob 

 shales of Clark county, Indiana. In northern Indiana Mr. Hop- 

 kins has called the massive sandstone which is quarried exten- 

 sively near Riverside P. O. the "Riverside sandstone." A study 

 of a colleaion of fossils from the Riverside quarries indicates the 

 identity of the Riverside sandstone of Hopkins and the upper di- 

 vision of the "Knobstone." 



The "Knobstones" were first classed with a portion of the 

 lyower Carboniferous limestones by Owen under the name of the 

 "Siliceocalcareous series"*. In the revised reprint of Owen's 

 Report published in i859t the name "knobstones" first appears. 

 It is used, according to the author, to designate "the fine grained 

 free-stones with subordinate beds of grey shales" of the Knob 

 regions. The name "Knobstone" has since been generally used 

 in the Indiana Reports. It is a topographic term derived from 

 the peculiar topographic forms developed in the Knob region of 

 southern Indiana. The name therefore violates the modern rule 

 of stratigraphic nomenclature, which requires the use of a definite 

 geographical name for a geological terrane. The names intro- 

 duced by Borden and Hopkins are used in the present paper in- 

 stead of "Knobstones" for this reason, and also because they in- 

 dicate the divisions of the "Knobstones," which are unlike faun- 

 ally and lithologically. 



The beds of this series reach their maximum development in 

 Brown county, Indiana, where they attain a thickness of about 

 six hundred feet and constitute the only surface rocks over a belt 

 of country more than twenty miles wide. To the north and 



*Geol. Recon. of Ind., p. 14, 1837. 

 fGeol. Recon. of Ind., p. 21, 1859. 



