54 
GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
Analyses of Davidson and Sumerford clays, Itawamba County. 
[By W. F. Hand, State chemist.! 
Davidson 
clay. 
Sumerford 
clay. 
59. 12 
62. 58 
27.44 
27. 58 
4.39 
1.57 
.34 
.40 
.28 
Trace. 
Trace. 
Trace. 
.54 
.77 
7.40 
6. 77 
Silica (SiOs) 
Alumina (A1 2 8 ) 
Ferric oxide (Fe20s). 
Lime (CaO) 
Magnesia (MgO) 
Sulphur trioxide (S0 3 ) 
Moisture 
Loss on ignition 
The analyses show the clays to be strikingly similar. The amount of silica and alumina 
in each is about equal. The Davidson clay contains more iron oxide than the Sumerford, 
though brick burned from the two clays at the same temperature show a slightly deeper 
pink for the Davidson clay. 
One mile north of the Sumerford pottery E. P. Kennedy has a jug factory. Apparently 
the -.nine si ml inn of clay is used at the two places. There is a greater thickness of Lafayette 
here than overlies the Sumerford clay, and the clay has a greater amount of iron oxide, as 
the analysis below will show. When burned the clay has a pink-buff color. 
Analysis of clay from Kennedy factory , Itawamba County. 
Silica (SiOs) 71. 53 
Alumina ( A1 2 3 ) 14. 46 
Ferric oxide (Fe 2 03) 4. 14 
Lime (CaO) 62 
Magnesia (MgO) 55 
Moisture 2. 17 
Loss on ignition 5. 91 
PORTERS CREEK CLAYS (LOWER EOCENE). 
The clays of this formation underlie the well-known "Flatwoods" lying west of the Ripley 
area in northern Mississippi and west of the Selma chalk area south of Houston, Chickasaw 
County. The clays embrace the upper division of the series shown on the map as Midway. 
North of Pontotoc the clays are underlain by 20 feet or more of calcareous sands and this, 
in turn, by about the same thickness of Turritella limestone. South of Pontotoc, however, 
the sands and limestone have not been found if present and the entire Midway is composed 
of the Porters Creek clays. 
There is a remarkable similarity in these clays throughout the State. When wet they are 
very stiff, of a gray or black color, but when dry they become a light gray to white. 
The entire "Flatwoods" area throughout the State has always been regarded as very poor 
agricultural land. The clayey soil is very poor in lime, phosphate, and other ingredients 
necessary to constitute fertility. The following analysis of the Porters Creek or Flatwoods 
clay soil was made by Dr. E. W. Hilgard:« 
Analysis of Porters Creek clay soil. 
Silica (SiOa) 77. 854 
Alumina (A1 2 3 ) 10. 302 
Ferric oxide (Fe 2 3 ) 5. 89 
Lime (CaO) 178 
Magnesia (MgO) s.U 
Potash (K a O) 753 
a Geology and Agriculture of Mississippi, 1860, p. 276. 
