THE DEEP WELL AT LAURENS, POCAHONTAS COUNTY 



E. J. CABLE 



The town of Laurens is located in the northwest corner of Poca- 

 hontas county. The surface drift within the county is Wisconsin, 

 while the underlying drifts are probably Kansan and Nebraskan. 



Feet Inches 



1. Black shale 3 6 



2. Yellow calcareous clay 10 



3. Blue clay, calcareous 206 



4. Sand and gravel 10 



5. Blue clay, compact, calcareous 20 



6. Sand 150 



7. Blue shale 50 



8. Limestone 285 



9. Blue shale 15 



10. Limestone 260 



11. Blue shale 80 



12. Sandstone 35 



1,125 



Horizons (1) to (3), inclusive, are Wisconsin drift. Horizon 

 (4) is probably interglacial and equivalent in time to the Aftonian 

 or Buchanan gravels. Horizon (5) is either Kansan or Nebraskan 

 drift with a strong probability of being Kansan. Horizons (6) and 

 (7) are undoubtedly Cretaceous, as Cretaceous deposits, consisting 

 of sand and shales, are found immediately beneath the drift in the 

 county. Horizon (8) may be Mississippian in age. Horizon (9) 

 has not been found previously in the county at this depth. The as- 

 signment of horizon (9) to the upper Ordovician, Maquoketa shale, 

 may be a possibility. If horizon (9) is Maquoketa shale, horizons 

 (10) and (11) are possibly Galena to Platteville, inclusive. 

 Horizon (12) is unquestionably Saint Peter sandstone, which is 

 an aquifer for deep wells in this locality. 



The Saint Peter is encountered at Emmetsburg, Palo Alto county, 

 at a depth of 864 feet, while at Laurens, it is reached at a depth 

 of 1,100 feet. The Saint Peter sandstone descends 252 feet in 21^ 

 miles, or at the rate of 11.85 feet to the mile. 



Department of Geology, 

 The State Teachers College. 



