williams.J ENGLEMANN. 163 



in either of the last two volumes. They are devoted to the elaboration 

 of the details of geology in the counties and to paleontology. 



Mr. Henry Engleniann, 1 in 1868, described the Lower Carboniferous 

 formations of southern Illinois as follows : 



Underlying the Coal Measures in central Illinois, Iowa, and Missouri, 

 were distinguished the following formations: 



1. The Ferruginous sandstone. 



2. The St. Louis limestone. 



3. The Warsaw limestone. 



4. The Keokuk limestone. 



5. The Encrinital or Burlington limestone. 



Farther south the " Kaskaskia or Chester limestone" was found be- 

 tween the Coal Measures and the Ferruginous sandstone ; and heavy 

 masses of sandstone ("Millstone grit") were observed next below 

 the Coal Measures, and also beds of sandstone intercalated with the 

 Chester limestone. 



The author discovered that in the extreme southern part of Illinois 

 this upper division of the Lower Carboniferous attains a much greater 

 and more varied development, while the lower subdivisions seen far- 

 ther north are lost or merged into one. He subdivided the series as 

 follows : 



A. Coal Measures. 



B. Millstone grit, reaching a thickness of 500 feet, with a seam of coal far above 

 the middle dividing it into Upper and Lower Millstone grit. 



C. Strata corresponding to the Chester limestone and Ferruginous sandstone, and 

 consisting of alternations of siliceous, Archimedes and Pentremital limestones, of 

 hales, and sandstones, attaining a maximum thickness in Johnson County and ad- 

 joining counties of 1,000 feet. 



The different layers of limestones aud sandstones are described in 

 detail. 



D. The St. Louis limestone, with a thickness of 200 feet or more. 



Some of the layers have an Oolitic structure. Underneath this are 

 shales, siliceous slates, and some black laminated slate, 2 considered by 

 good authorities as of the age of the Chemung group. Below these are 

 well marked Devonian strata. 



The general features of the geology of Tennessee were defined in 

 the various reports of Gerard Troost, and some of the names which 

 have been preserved were proposed by him. 



In 1869 appeared Safford's " Geology of Tennessee," which elaborates 

 the work begun by Mr. Troost, and presents a systematic classification 



'Englemann, Henry: On the Lower Carboniferous system as developed in southern Illinois. St. 

 Louis Acad. Sci., Trans., vol. 2, 1868, pp. 188-190. 



2 This paper was written later than the publication of the first Report of the Geological Survey of 

 Illinois, in which, as is quoted on a previous page, the name " Chester group,"' was proposed to include 

 the formations which had previously gone under the names "Kaskaskia limestone," "Ferruginous 

 sandstone," and " Chester limestone." 



Dr. Englemann, who was at the time of writing this paper (1868) one of the geologists on the survey 

 of Illinois, elaborates the facts as exhibited in southern Illinois. 



