Front Matter
Articles
Annual Report of the Director p. i-xx
George F. Kay
Mineral Production in Iowa in 1919 and 1920 p. xxi-xlviii
James H. Lees
Petroleum and Natural Gas in Iowa p. 1-48
Jesse V. Howell
The Origin and History of Extinct Lake Calvin p. 49-222
Walter H. Schoewe
The Missouri Series of the Pennsylvanian System in Southwestern Iowa p. 223-314
John L. Tilton
New Echinoderms from the Maquoketa Beds of Fayette County, Iowa p. 315-384
Arthur Ware Slocom and August F. Foerste
Echinoderms of the Iowa Devonian p. 385-552
A. O. Thomas