76 DEPOSITS OF PHOSPHATE OF LIME, [bull. 46. 
half an inch to three inches in diameter. They are very irregular in 
form and occasionally show one side which is completely phosphatized 
and another which is composed largely of carbonate of lime. This is 
strong evidence for the theory of their formation by the phosphatiza- 
tion of the surface of a calcareous bed, as mentioned in the case of the 
North Carolina deposits. The fossils of the two beds differ considera- 
bly. Ammonites are very plentiful in both, but Hippurites and Baca- 
lites were found in much larger quantities in the lower bed than in the 
upper one. The following two sections will show the different relations 
of the two beds : 
(a) Upper bed (at Coatopa) : 
1. Greeusand containing nodules and shell casts, but numerous only at the base, 
4 feet. 
2. Soft, calcareous rock containing nodules, 1 foot to 1^ feet. 
3. Rotten limestone. 
(b) Lower bed (at Hamburg) : 
1. Greeusand bearing some casts and nodules, to 5 feet. 
2. Gray limestone containing mauy nodules, 5 feet. 
3. Hard, indurated sand ledge, containing shells, 8 to 12 inches. 
4. Yellow sand containing shells, 2 feet. 
5. Ferruginous sand containing specks of mipa, about SO feet, 
C. Indurated sand ledge containing shells 8 to 12 inches. 
7. Yellow sand containing shells, 2 feet. 
8. Greensand. 
The section of the upper bed is well seen at the town of Coatopa, in 
Sumter County. The Greensand here is often oxidized and has a rusty- 
red appearance; it composes a large part of the surface sod in the 
neighborhood and forms part of the so-called " Black Belt," famous 
for its fertility. It contains many phosphatic shell casts, but is gener- 
ally richest in them near the line of contact with the underlying bed, 
where they sometimes make up 50 per cent, of the whole mass. Occa- 
sionally they cover the whole surface of the ground and must be carted 
away in order to permit agricultural operations. The underlying bed 
contains many more nodules and shell casts than the Greensand. 
Sometimes it is almost a solid mass of them with a soft, gray, calcareous 
matrix. The bed is from 1 foot to 1J feet thick and seems to underlie 
a large extent of country. In some places the nodules and fossils are 
more scattered in the bed than in others, and in still other places the 
bed has been entirely eroded away and the Greensand comes into 
direct contact with the Kotten Limestone. Very few bones were found 
in this upper bed. 
Outcrops of this same nodule bed can be seen near the Tombigbee 
River, at Moscow, and also at Livingston, on the Sucarnochee River. 
In the underlying Botten Limestone there are no phosphatic nodules. 
The section of the lower nodule bed is seen at numerous places all 
across the State. Thus it is found at Eutaw, Selma, Greenborough, 
Prattville, Wetumpka, and especially well at Hamburg, near Marion. 
(550) 
