Stoux City Academy of Science and Letters. 149 
SECTION AT SIDE OF RAVINE, SEC. 14, T. 29 N., R. 7 E. 
Thickness 
Feet. 
Recent { 6. Loess slope at elevation of 1210 feet........... 
Graneros { FMS Ale voraiy Phi SSM a ans ecules uaa ueaatalore lasieate 2 
4. Sandstone, friable, gray to rusty, with plant 
TETIVALINS fee ey octara ae rn ale reece coe artsyradeanreutaria ahaa ve netiota ts 6 
Daokta 8. Sandstone, hard, yellowish ........6.....0000% 3 
Clay, sandy, light buff to yellow, some hard 
HAVENS Mi aisrste lay apse an onainvoraied euciie leech aes Beane reuale tarts e alleys 25 
1. Shale, yellow, fissile, “‘soapstone” ............. 22 
Elevation at base, 1155 feet. 
Other excellent sections were studied farther north, 
in Dixon County, near the mouth of Aowa Creek, where 
the beds appear to have more than their ordinary dip to 
the northwest. Beyond the mouth of Aowa Creek the 
beds continue nearly horizontal for a short distance, after 
which they disappear below the level of Missouri River. 
The individual beds of the Dakota do not seem to be 
sufficiently persistent for correlation over any consider- 
able distance. At the top is a bed of porous, friable 
sandstone containing leaf and plant remains, and be- 
low it a thin series of interstratified clays, sands, and 
lignite seams is fairly constant. Below this lies a thin 
series of clays, sandy shales, and ferruginous, siliceous 
seams, and the horizon of massive, cross-bedded sand- 
stone still lower down is somewhat distinct at the 
south end of the county. Drillings in various parts of 
the county substantiate the above general order of 
the beds, but drill holes within a few rods of each 
other show a remarkable diversity between the smaller 
divisions of the strata. The thickness of the Dakota 
can be estimated only from the data afforded by the 
wells at Ponca, Nebraska, and at Sioux City, Iowa, where 
it has been passed through. The Sioux City well, con- 
sidering that 25 feet of the sandstone has been removed 
by erosion from the topmost beds now visible, indicates a 
thickness of 325 feet. At Ponca a thickness of 375 feet 
is shown. 
Benton group.—Lying conformably on the Dakota are 
dark-gray to dark-bluish shales and clays. These repre- 
sent the base of the Benton, and are here called the Gran- 
eros shales in the belief that they correspond to that 
