|Latitude & Longitude (WGS84):||39° 59' North , 91° 37' West|
|Latitude & Longitude (decimal):||39.98333,-91.61667|
|Köppen climate type:||Dfa : Hot-summer humid continental climate|
An outcrop of the geode-bearing Mississippian age Keokuk formation. Geodes at this site have been found up to 25 cm in diameter and are usually lined with colorless quartz or chalcedony, with a variety of accessory minerals.
11 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
252.17 - 541 Ma
|Paleozoic sedimentary rocks|
Age: Paleozoic (252.17 - 541 Ma)
Lithology: Sedimentary rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
323.2 - 358.9 Ma
Age: Mississippian (323.2 - 358.9 Ma)
Comments: Keokuk Limestone- (100 ft. max) limestone with chert nodules, including Short Creek Oolite member- (8 ft. max) oolitic limestone; Burlington Limestone- (70 ft. max) white fossiliferous limestone with chert nodules; Elesey FM (or Grand Falls FM) (100 ft. max) gray limestone with chert nodules; Reeds Spring FM- (225 ft. max) alternating bands of dolomitic limestone with chert nodules; Pierson Limestone- (60 ft. max) dolomite and dolomitic limestone with chert nodules; Fern Glen FM- (45 ft. max) red limestone with some red calcareous, fossiliferous shale. The Keokuk Limestone and parts of the Reeds Springs FM are host to Mississippi Valley type Pb-Zn deposits in the Tri State District. The major commodity is zinc, from sphalerite, galena ore. IN SOUTHWEST MO-Keokuk Limestone, Burlington Limestone, Elesey FM, Reeds Spring FM, Pierson Limestone. IN CENTRAL MO- Keokuk Limestone, Burlington Limestone, Pierson Limestone. IN NORTHEAST MO- Keokuk Limestone, Burlington Limestone. IN EAST-CENTRAL MO- Keokuk Limestone, Burlington Limeston, Fern Glen FM. IN SOUTHEAST MO- Keokuk Limestone, Burlington Limeston, Fern Glen FM.
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.