DETAILED RECORDS. 267 
Eocene — Continued. Feet. 
Tough gray marl (fossiliferous) 160-190 
Water stratum (gray sand, white sand, and coarse quartz gravel). 190-208 
Fine gray sand and marl 208-228 
Rig used, rotary and jet. Diameter of wells, 4| inches. Length of casing, about 60 feet. 
Water rises to 12 feet from surface; pumping 400 gallons per minute from three wells; 
depressed head about 80 feet. Quality, hard. 
SOUTH DAKOTA. 
1455. Well 11 miles west of Cartilage, Beadle County. 
[Well begun October 30, 1904; completed November G, 1904. Authority, H. B. Potter, contractor and 
driller. No samples. Geologic correlations checked by N. H. Darton.] 
This flowing well in the southeastern part of Beadle County obtains water from the 
Dakota sandstone. The formations penetrated are the drift (Pleistocene) and underlying 
rocks of Cretaceous age, the Pierre shale, and the Niobrara, Benton, and Dakota formations. 
The geology of the surrounding region and the depths to the water-bearing formations are 
discussed in the Huron and De Smet folios (Nos. 113 and 114) of the Geologic Atlas of the 
United States. 
Record of well in the SW. \ SW. \ sec. 26, T. 109, R. 59. 
Drift and Pierre: Feet. 
Clay and shale 1-326 
Niobrara : 
Chalk rock. 326-335 
Niobrara and Benton: 
Hard layers with soft material between, black oily substance 335-350 
Blue shale with hard layers 350-500 
Sandstone and hard layers 500-700 
Dakota : 
Cap rock 6 inches thick 767 
Dakota sandstone 767-818 
Rig used, jet. Casing used, 804 feet of 2-inch. Flow, 85 gallons per minute. 
1458a. Well near Ro swell, Miner County. 
[Well begun November 22, 1905; completed December 10, 1905. Authority, IT. B. Potter, driller. No 
samples. Geologic correlations checked by N. II. Darton.] 
This well is one of the many in the Dakotas obtaining flowing water from the Dakota 
sandstone. The formations underlying the Glacial clay, sand, and gravel are of Cretaceous 
age. Their order, from top to bottom, is as follows: Pierre, Niobrara, Benton, and Dakota. 
Record of well in the SE. \ sec. 31, T. 107, R. 57. 
Drift : Feet. 
Clay : 1- 4 
Sand and gravel 4- 50 
Blue clay 50- SO 
Pierre : 
Shale 90-290 
Niobrara : 
Chalk rock 290-340 
Niobrara and Benton : 
Shale and soft shale 340-582 
Shale with hard layers, 12 in all, very hard layer at 633-634 feet 582-634 
Dakota: 
Sandstone 634-672 
Honeycomb sandstone, very porous 672-710 
Rig used, jet. Casing used, 696 feet of 2-inch. Well flows 95 gallons per minute ; quality 
of water, soft. 
