J. C. Branner — Paleozoic Sediments in Arkansas. 235 



In the Lower Coal Measures area lying south of the Oua- 

 chita uplift Dr. George H. Ashley, who worked out the details 

 of the geology of that region, found 5200 feet of sediments 

 above the Silurian on West Saline Eiver, and on the Rolling 

 Fork of Little River he found 6800 feet, with the bottom still 

 concealed. 



These sediments are overlapped by the Cretaceous rocks to 

 the south, so that the total thickness of the beds on that side 

 of the Ouachita uplift is not visible. 



Table of Thickness of the Paleozoic Sediments of Arkansas. 



Bost. Ark, 

 Mts. Valley, 

 feet. feet. 



rTT n 1 AT i Poteau beds 3500 



P 1M r Upper Coal M. Productive beds . 1800 



Coal Measures ^ | ^ 



or >• <( Lower Coal M. Barren beds 18480 



Pennsylvanian ) | 



(^" Millstone grit". 500 



Lower f " Chester, St. Louis ") t? . ^ar^ 



)arboni. | " Warsa^ " \ ^°^*- S-^""?- " " " ^^° 



Carboni 

 ferous or ^ 



Missis- 



sippian, 



"TT ir V" ) fBatesville sandstone. 200 

 ^eoKUK / I Fayetteville shale... 300 



"Burlington" s -nr j ^ 



Wyman sandstone .. 10 

 1^ Boone chert 370 



De-iann { KnhX':"!!: to 



Upper Silurian.. T St. Clair Marble 155 



Lower Silurian < Izard limestone 285 



( Underlying beds -..1750 



+ + 



4440 23,780 + 

 Total thickness of known Paleozoic sediments 28,220 feet. 



There is, of course, nothing remarkable about the thickness 

 of any of the Arkansas sediments except in the case of the 

 Lower Coal Measures. So far as I can learn, the thickness of 

 the Carboniferous rocks in this section is greater than that of 

 sediments of the same age in other parts of the country or of 

 the world. 



Hitherto the Carboniferous sediments of Nova Scotia have 

 been looked upon as the thickest on the Continent — between 

 10,000 and 16,000 feet.* 



* There has been some disagreement about the thickness of these beds. Sir 

 "Wm. Logan reported 14,570 feet; later Sir Wm. Dawson gave 10,000 feet for 

 the Coal Measm-es proper (Proc. Am. Phil. Soc. 1862, ix, 101 ; 1863, ix, 208 ; 



