CRETACEOUS LIMESTONE. 79 
Analysis ofSelma limestone from Bodea < 'reek, near Scooba. 
[By W. S. S£c>Tc;l.] 
Silica (Si0 2 ) 10. 60 
Alumina ( A1 2 3 ) I 
Iron oxide (Fe 2 3 ) I ' ''" 
Lime carbonate (CaC0 3 ) 82. 47 
Magnesium carbonate (MgC0 3 ) Trace. 
Water 82 
Three miles north of Scooba the western border of the Selma chalk outcrops in a series of 
hills forming the south bank of Wahalak Creek. The bottom of the Wahalak is here U 
miles wide, the south bank retreating more rapidly than the north side. The creek has i-m 
its channel into the Selma chalk, which outcrops almost continuously throughout its course. 
The limestone occurs up the creek about 6g to 7 miles northwest of Wahalak, but the Porters 
Creek clay occupies the country on both sides of the creek. The hill just east of Wahalak is 
of Porters Creek clay, which is not over 15 feet thick. 
A sample of limestone was collected from the bed of Wahalak Creek, about I2 miles south 
of Wahalak. This sample was analyzed in the laboratory of the United States Geological 
Survey, with the following results: 
Analysis of Selma limestone from Wahalak Creek, near Wahalak. 
[By \V. S. McNeil.] 
Silica (Si0 2 ) , 20. 00 
Alumina (A1 2 3 ) 1 g g2 
Iron oxide (Fe 2 3 ) J 
Lime carbonate (CaC0 3 ) 68. 91 
Magnesium ear! 1 Eg< I ) ) .- Trace. 
Water 1.03 
A sample of the Selma limestone was taken from the bed of Wahalak Creek, 1^ miles south 
of the town, and on the range of low hills south of Wahalak Creek, 1^ miles southeast of the 
point where the Mobile and Ohio Railroad crosses the creek, another sample was taken. At 
the top of the Selma chalk there is about 10 feet of a sand rock cemented with lime car- 
bonate, which contains numerous little bivalve shells. This is the same kind of stone as 
that found 7 miles east of Sucarnochee. There is no evidence of any Clayton limestone any- 
where from Wahalak to the Alabama line, and this is the only place where the sandstone 
was seen in Mississippi. This doubtless belongs to the Ripley. 
The Porters Creek or Flatwoods clay is well shown near Scooba. A sample collected 
wa analyzed in the laboratory of the United States Geological Survey. The result is of 
interest, because clays of this type occur everywhere near the western <'(\x<- of the Selma 
limestone area, and such clays will be needed to reduce the percentage of lime carbonate 
found in some of the purer samples of Selma chalk. 
Analysis of Midway clay from Scooba. 
[By W. S. McNeil.] 
Silica (Si0 2 ) 61-92 
Alumina ( A1 2 3 ) 19. 47 
[ron oxide (Fe 2 3 ) 2. 81 
Magnesia (MgO) -•- 1-98 
3oda (Na 2 0) 50 
oss on ignition 12. 29 
A sample of Selma chalk was taken from an old rock quarry sil ua ted on the southwest side 
Df Bogue Chitto Creek,one-half mile east of Prairie Rock. This limestone differs from t hat 
long Oaknoxubee River, in the vicinity of Macon, in that it is much harder. In the un- 
fathered state of the Macon rock, it is very soft and noncrystalline. One can easily -1 i< I. 
1 pick into it. But the limestone at Prairie Rock is a hard so-called "flint rock.'' crysl alline 
n character, and is u ed for building purposes. The rock at Macon, when exposed to the 
