Table 1.--Generalized section of geologic formations
and their water-bearing properties* (from Gutentag et al., 1981).
|
|
|
unit |
Feet |
|
|
| Quaternary | Pleistocene | Alluvium | 0-80 | Stream-laid deposits ranging from
silt and clay to
sand and gravel that occur along principal stream valleys. |
Yields to wells range from 500
to more than 1,000 gal/min in the Arkansas
River valley; 50 to 500 gal/min in the Pawnee River valley; and 50 to 1,000 gal/min in the Cimarron River valley. |
| Dune sand | 0-75 | Fine to medium quartzose sand with small amounts of clay, silt, and coarse sand formed into mounds and ridges by the wind. | Lies above the water table and
does
not yield water to wells. The sand has a high infiltration rate and is important as area of ground- water recharge. |
||
| Loess | 0-45 | Silt with subordinate amounts
of very fine sand
and clay deposited as windblown dust. |
Lies above the water table and
doesnot yield water to wells. Serves as
minor area of ground-water recharge. |
||
| Undifferentiated
deposits |
0-550 | Sand, gravel, silt, clay, and
caliche overlie
Ogallala Formation when both formations are present;composite of stream-laid and windblown deposits. |
The sand and gravel of the undiffer-
entiated Pleistocene deposits and the Ogallala Formation are the |
||
| Tertiary | Pliocene | Ogallala
Formation |
0-500 | Poorly sorted clay, silt, sand,
and gravel generally
calcareous; when cemented by calcium carbonate, Forms caliche layers or mortar beds. |
principal water-bearing deposits
in
the area. Yields range from 100 to 3,100 gal/min. |
| Cretaceous | Upper Cretaceous | Niobrara Chalk | 0-250 | Upper unit (Smoky Hill Chalk Member)--yellow
to
orange-yellow chalk and light- to dark-gray beds of chalky shale. Lower unit (Fort Hays Limestone Member)--consists of a white to yellow massive chalky limestone: contains thin beds of dark-gray chalky shale. |
Generally not considered an aquifer.
Initially (1968-72), yielded 500 to
2,500 gal/min to wells in northern Finney and eastern Kearny Counties where the Fort Hays Limestone Member has been honeycombed by fractures and solution openings. Because of increased irrigation development, yields have been reduced by 100 to as much as 2,000 gal/min. |
| Carlile Shale | 0-330 | Upper unit consists of a dark-gray
to blue-black
noncalcareous to slightly calcareous shale that locally is interbedded with calcareous silty very fine-grained sandstone. Lower part consists of very calcareous dark-gray shale and thin gray interbedded limestone layers. |
Sandstone in upper part may yield
5 to 10 gal/min to wells. |
||
| Greenhorn
Limestone |
0-200 | Chalky light yellow-brown shale
with thin-bedded
limestone. Dark-gray calcareous shale and light- gray thin-bedded limestone; contains layers of bentonite. |
Not known to yield water to wells
in southwestern Kansas. |
| Graneros
Shale |
0-130 | Dark-gray calcareous shale interbedded
with black
calcareous shale; contains thin beds of bentonite. Also contains thin-bedded gray limestone and fine- grained silty sandstone layers. |
Not known to yield water to wells
in southwestern Kansas. |
||
| Lower Cretaceous | Undifferentiated
rocks |
0-450 | Upper unit (Dakota Formation)--brown
to gray fine-
to medium-grained sandstone; interbedded with gray sandy shale and varicolored shale; contains lignite lenses (0-160 feet). Middle unit (Kiowa Formation)--dark-gray to black shale; interbedded with light yellow-brown and gray sandstone (0-150 feet). Lower unit (Cheyenne Sandstone)--gray and brown very fine-to medium-grained sandstone; interbedded with dark-gray shale (0-125 feet). |
The sandstone units commonly yield
from 50 to 500 gal/min to wells. Yields of more than 1,000 gal/min are reported in a few areas. Water may be more mineralized in the lo- wer unit than in the upper unit. |
|
| Jurassic | Upper Jurassic | Undifferentiated
rocks |
0-350 | Dark-gray shale; interbedded with
grayish-green and
bluish-green calcareous shale. Contains very fine- to medium-grained silty sandstone and some thin limestone beds at the base. |
In Morton and Stanton Counties,
sand-stone beds are yielding in combination with the overlying Lower Cretaceous
units. In the northernmost
counties where the aquifer is deepest, the water may be mineralized. |
| Permian | Upper
Permian |
Big Basin
Formation |
0-160 | Brick-red to maroon siltstone
and shale; contains
very fine-grained sandstone. |
Where not highly mineralized,
may
yield small quantities of usable water for domestic and stock pur- poses. |
| Day Creek
Dolomite |
0-80 | White to pink anhydrite and gypsum;
contains inter-
bedded dark-red shale. |
Solution cavities have yielded
large
quantities (300 to 1,000 gal/min) of high sulfate water to wells in Morton County. |
||
| Whitehorse
Formation |
100-350 | Red to maroon fine-grained silty sandstone, silt-stone, and shale. | Fresh to highly mineralized water.
Not known to yield significant amounts of water to wells in south- western Kansas. |
||
| Lower
Permian |
Dog Creek
Formation |
15-60 | Maroon silty shale, siltstone,
very fine sand-
stone, and thin layers of dolomite and gypsum.
|
Not known to yield significant
amounts of water to wells in south- western Kansas. Water probably highly mineralized. |
|
| Blaine
Formation |
20-150 | Generally consists of four gypsum
and anhydrite
beds separated by red shale; contains bedded ha- lite at some sites. |
Not known to yield significant
amounts of water to wells in south- western Kansas. Water probably highly mineralized.
|
*The classification and nomenclature of the stratigraphic units used in this report are those of the Kansas Geological Survey and differ somewhat from those of the U.S. Geological Survey