STRATIGRAPHIC SUMMARY 



STRATIGRAPHIC SUMMARY 



The Chouteau limestone in Missouri, as 

 originally defined by Swallow (1855, p. 

 101), consists of an upper 40- to 50-foot 

 thick-bedded limestone and of a lower 20- 

 foot thin-bedded limestone. The type section 

 at Chouteau Springs, Cooper County, Mis- 

 souri, was described by Moore (1928, p. 

 84) as consisting of an upper member 30 

 feet thick and a lower member 20 feet thick. 

 At a quarry in Sweeney, Cooper County, 

 Moore (1928, p. 85) recorded 43 feet 6 

 inches of limestone in the upper member, 

 which is separated by a possible disconform- 

 ity from 25 feet 8 inches of limestone in the 

 lower member. Previous to the appearance 

 of Moore's paper, the upper and lower beds 

 were sometimes distinguished but they were 

 always considered to be subdivisions of a 

 single formation. Moore, however, re- 

 stricted use of the name Chouteau to the 

 lower beds, of Kinderhook age, and pro- 

 posed the name Sedalia limestone for the 

 upper beds, which he assigned to the Osage 

 group and correlated somewhat tentatively 

 with the Fern Glen formation. The latter 

 usage is accepted by the United States Geo- 

 logical Survey (Wilmarth, 1938, p. 439). 



One mile north of Sedalia, Pettis County, 

 Missouri, Moore (1928, p. 86) recorded 18 

 feet 2 inches of Sedalia limestone overlying 

 6 feet 5 inches of exposed Chouteau lime- 

 stone. Many of the original Chouteau col- 

 lections were made from the quarries near 

 Sedalia. 



In the river bluffs at Providence, Boone 

 County, Missouri, Moore (1928, p. 88) 

 recorded 21^ feet of Sedalia limestone and 

 42^^ feet of Chouteau limestone. Many 

 fossils have been collected from this lo- 

 cality. 



Some 25 miles southwest of St. Louis a 

 good exposure contains about 7 feet of 

 Chouteau limestone, according to McQueen 

 (1939, p. 97), who referred higher sandy 

 shales and cherty limestones at that place 

 to the Sedalia which he considered to be 

 equivalent to the ''lower Fern Glen." 

 Sandstone and sandy shale between these 

 formations were identified as Northview 

 sandstone. 



A composite section (after Weller, 1941, 

 pp. 72, 73) based on outcrops on both sides 

 of Mississippi River near Hannibal, Mis- 

 souri, shows the following beds to occur in 

 sequence below the widespread Burlington 



limestone: Prospect Hill sandstone, Mc- 

 Craney limestone, English River sandstone, 

 Hannibal (or Maple Mill) shale, and 

 Louisiana limestone. Corals with close 

 Chouteau affinities are known from the 

 McCraney and Prospect Hill, these being 

 the beds of the Burlington, Iowa, section 

 from which the types of Leptopora typa 

 were collected. 



Near Jerseyville, Illinois, is a very thick 

 section of Chouteau limestone underlain in 

 order by the Maple Mill shale, Hamburg 

 beds, and Grassy-Saverton shale of J. M. 

 Weller. The Hamburg beds are presumed 

 to be equivalent to the Glen Park lime- 

 stone. Corals have been collected from the 

 Chouteau limestone at a locality northwest 

 of Jerseyville. The Sedalia limestone is pos- 

 sibly present here above typical Chouteau. 



The Springville shale of Union County, 

 Illinois, contains glauconitic limestone beds 

 near the base from which corals of Chou- 

 teau affinity have been collected. It has been 

 considered by Weller and Sutton (1940, 

 p. 766) to be equivalent to the Hannibal 

 shale. 



The Rockford limestone of Indiana is a 

 thin glauconitic limestone- overlain by 

 Osage siltstone and underlain by a few 

 inches of calcareous shale. Most of the col- 

 lections from the "Rockford beds" were 

 made many years ago and the fossils are 

 reputed to have been collected from argilla- 

 ceous limestone or calcareous shale either 

 overlying or grading down into the typical 

 Rockford limestone. The thin shale under- 

 lying the Rockford limestone also carries 

 corals. 



The Hampton formation of Iowa consists 

 of four members in the north central part 

 of the outcrop area; these members are, in 

 descending order, the Iowa Falls, Eagle 

 City, Maynes Creek, and Chapin. In the 

 southeastern part of the outcrop area the 

 Hampton formation consists of the Wasson- 

 ville member, underlain by the North Hill 

 member. The Wassonville is equivalent to 

 the Maynes Creek, and the North Hill is 

 equivalent to the Chapin. The Iowa Falls 

 and Eagle City are thought to be younger 

 than the Chouteau (restricted), and the 

 faunas are said to be derived from the Chou- 

 teau (Laudon, 1931, p. 348). The rest of 

 the Hampton formation is thought to be 

 equivalent to the Chouteau. 



