INTRODUCTION. 



The data for the report contained in this bulletin were 

 collected by the writer and his assistants during six field seasons. 

 During June, July, and August of 1914, J. P. Connolly and 

 Chester Longwell assisted in mapping and collecting; Mr. 

 Connolly mapped during June of 1915; in June and July of 1917, 

 several advanced students assisted in mapping and collecting; 

 G. P. Moore and E. 0. Markham were field assistants the summer 

 of 1918; V. W. Vandiver collected during July and August of 

 1919; G. P. Moore and V. W. Vandiver mapped the Devonian 

 of Ralls County in 1919; and Roy H. Hall mapped part of 

 Moniteau County in 1921. Mr. D. K. Greger knew the Devonian 

 of Callaway County very thoroughly before the field work for 

 the report was begun and helped out the investigation from his 

 information. He collected from the Devonian of Montgomery 

 County during June and part of July, 1914. 



The topographic maps of the United States Geological 

 Survey for the region studied are old, half-inch scale, and fifty- 

 foot contour interval, and are entirely unsatisfactory for accurate 

 mapping. The base finally used for most of the work was a 

 large scale county map with contour lines supplied from the 

 United States Geological Survey contour maps. The contours 

 were corrected to make them fit conditions as found in the field. 

 A two-inch scale was used for all mapping in Boone, Callaway, 

 Montgomery, Warren and Moniteau Counties, and the U. S. 

 Geological Survey topographic maps were the base for the other 

 areas. 



Contacts were not walked out but valleys were sectioned 

 every half-mile or mile and if irregularities were present the 

 contacts were followed in more detail. Half of the work was 

 intrusted to advanced students but all irregularities were 

 checked by the writer and all pinching out or appearances of 

 formations were also investigated by him. 



G. P. Moore is responsible for the Ralls County map though 

 the writer visited the area of outcrops twice to check up the 

 stratigraphy. Marion County was visited once by D. K. Greger 



(viii) 



