82 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
Analysis ofSelma limestone from 6 miles north of Macon. 
i A . S Mc sTeil.] 
Silica ( Si< > 2 ) - 8 - 52 
Alumina ( A.I2O3) I fi 6Q 
Iron oxide I FesOs) ' 
Lime carbonate aC0 3 ) 83.8] 
Water [.<■ 
Farther south, along the Macon and Columbus road, t ho limestone begins to show in 
every gully and on every hillside. \i some places on level ground the soil is not over 12 
inches deep. In this vicinity are the bald prairies, where large areas of this white limestone 
are .exposed without a particle of soil or a blade of grass. A sample of the rock was taken 
3 miles north of Macon. 
A sample of Selma limestone was taken at a point north of Lime Rock, 5 miles east q 
Shuqualak, on Oaknoxubee River, where a bluff 50 feet high is composed of typical Selmj 
chalk. The following analysis of this sample was made in the laboratory of the Unite( 
State- Geological Survey: 
Analysis of Selma linn stont from bluff near Shuqualak. 
[By W. S. McNeil. 1 
Sil tea (Si0 2 ) 8 - 
Alumina U l 5 „ 
J 
Lime carbon - 84.6 
Magnesium carbons ' Mg< ' h) 06 
Water 1.3 
Tombigbee River at Columbus has cut its channel into the Eutaw sands, forming a blui 
on the east side 90 feet high. The material composing the hind' here is a sand that is green 
ish when wet and gray when dry. It contain-, a small amount of lime carbonate. In tin 
upper part of the bluff the sands a re of lighter color and at the top they are a light golden yel- 
low. This was the color of the sand when deposited and is not due to oxidation. Numerou 
little branching concretions, which are perhaps some kind of badly preserved fossils, occu 
in the lower portion near the water. The upper part of the sands contains two species d 
large oysters, which also occur in the Selma. The river at the town is now hugging tin 
east bluff, and the bottom, which is •'! miles wide, is all on the west side. A short distancj 
above the town, however, the reverse i> true, the bluff being on the west side and the hot 
loin on the east. At the west edge of the bottom the heavy, black prairie soils of tin 
Selma chalk appear as SOOn as the little hill- are reached. The bottom extends northward 
to the little creek that (lows northeastward into the river .'! miles above the town. 
At a distance of I miles above town the bluff on the west side of the ri\er reaches abou 
the same height above t he water as the bin If at Columbus. It extends for 1 mile along the 
river as a perpendicular cliff that affords a fine section of the upper Eutaw and the base o 
the Selma. The low hills on the west come down to the top of the bluff. The same heavy 
black prairie soils which come within 3 miles of the river due west of Columbus here reach 
the edge of the bluff. 
The following i- a section of the bluff obtained where the road comes down to the river 
Section of bluff of Tombiybee River Jf.miles north of Columbus. 
Lafayette at top. 
Selma: Ft. in. 
10. "Blue rock" of the Selma; a white to gray joint clay containing less sand at top than at 
bottom. In its unweathered condition theclay is pale nine, with green and black sand. . 8 
Eutaw: 
9. Greensand, highly calcareous, and containing numerous large oysters 5 
8. Ledge of indurated greensand, calcareou , an 1 containing -a me fossils as No. 9 ll 
7. Lighter colored sand, containing very few small fossils and no large ones 14 
ti Greensand, nonfossiliferous 
