472 IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



Murchison's and Sedgwick's rock formations of England had no 

 connection with the geology of the region which he traversed. 



In Ohio, Locke* and Mather,^ and in Indiana, Owen,® had already 

 used the term Cliff Limestone for what they thought was the strati- 

 graphical equivalent of the English Cliff formation. This name was 

 an adaptation of the Scottish word Scar Limestone, and Sedgwick's 

 designation of the Carbonic limestone of the Lake District and of 

 Yorkshire. Even so late as 1840 Owen^ was inclined to regard the 

 Mountain Limestone section as extending downward to what was 

 afterward known as the St. Peter Sandstone, which latter he then 

 considered to be the Old Red Sandstone or Devonian. It was only 

 years subsequently that the Cliff Limestone was, after repeated re- 

 strictions, finally made the equivalent of the Niagara Limestone of 

 New York. It was Owen,* also, who, suspecting something wrong 

 in the prevailing correlations, proposed to call the section between 

 the Coal Measures and the St. Peter Sandstone the sub-Carboni- 

 ferous limestones. 



This, then, was the state of knowledge concerning the forma- 

 tions below the Coal Measures when the term St. Louis Limestone 

 first appeared as a distinctive geological title. When, in 1847, it 

 was thought necessary especially to designate "the thick limestone 

 which underlay the western edge of the great Illinois coal field," 

 and Dr. Henry Englemann" proposed therefor the title St. Louis 

 Limestone, its terranal limitations were, according to present day 

 standards, rather vaguely defined. The then recent efforts of Dr. 

 David Dale Owen, in his Iowa work, to introduce the English 

 classification of geological formations had a profound influence 

 upon the little coterie of geologists which was beginning to occupy 

 the field of the Mississippi valley and which made its headquarters 

 in the city of St. Louis. The naming of the St. Louis Limestone 

 was a phase of the American sub-Carboniferous question, and the 

 problem of the American Paleozoic. It was an attempt at adjust- 

 ment of the rocks of the continental interior with the general sec- 

 tion of Europe. 



Two years later, in a letter dated January 14, 1849, to the distin- 

 guished paleontologist. Dr. Verneuel, of Paris, Owen uses the term 

 St. Louis Limestone. Shortly after its receipt this letter was pub- 



*American Jour. Sci., (1), Vol. XL, p. 128, 1838. 



'Ohio Geol. Surv., 2nd Ann. Rept, pp. 1-40, 1838. 



•Indiana Geol. Surv., 2nd Kept., p. 17, 1839. 



'Rept. Geol. Bxpl. Iowa, Wisconsin and Illinois, p. 14, 1840. 



*Rept. Geol. Reconnolssance of the State of Indiana, etc., 44 pp., 1839. 



»Am. Jour. Sci., (1), Vol. Ill, p. 119, 1847. 



