SancLstonc 



CHESTER BEDS. 75 



cessive attenuations of the several beds and by the deeply ex- 

 cavated ravines, where soon afterward were laid down the local 

 sandstones and shales of the Goal Measures. In a number of 

 cases, at least, these hardened sand accumulations, lying in 

 narrow gorges, have been regarded erroneously as local depo- 

 sitions of Kaskaskia grit, intercalated in the shales and lime- 

 stone. Furthermore, these 

 consolidated sands contain 

 plant remains, and inasmuch 

 as they have been considered 

 Limesiotie ~ as part of the Kaskaskia, it 



Fig. 7. Detailsof Juncture of Figure 6. is quitC probable that this 



will account for some of the reported discoveries of certain 

 terrestrial floras in the rocks of the Mississippian series. 



Fauually, and especially stratigraphically, the Kaskaskia, 

 as displayed everywhere over a broad area adjacent to the line 

 of the Mississippi river, appears separated from the Saint Louis 

 far more widely than any other two members of the entire 

 Lower Carboniferous in the continental interior. 



The term "Chester" has been used by some authors for the 

 beds here designated as Kaskaskia. There seems to be, how- 

 ever, but little doubt that the latter name was published several 

 jears before Chester made its appearance in print. To be sure, 

 Worthen, while an assistant of I^orwood on the geological sur- 

 vey of Illinois, did suggest orally, or in his manuscript notes, 

 as early as 1853, the name of "Chester" for the beds in question, 

 but the name was known for several years only to members of 

 l^orwood's corps, as Worthen himself says.* It was at least a 

 dozen years later before the term was published with definite 

 stratigraphical significance, and then with the full knowledge 

 that it covered the same ground as Hall's "Kaskaskia." Hall, 

 as early as 1856, read a paper before the Albany Institute in 

 which he proposed a classification of the Lower Carboniferous 

 of the Mississippi basin, and two years later he published 

 essentially the same scheme in his Iowa report, f accompanied 



*Geol. Sar. Illinois, vol. I, p. 41. 1866. 

 tGeol. Iowa, vol. I, p. 109. 1858. 



