EL.] 
ARKANSAS. 
93 
Except where deeply stained with manganese and iron the St. Clair 
Linestone is a remarkably pure carbonate of lime. 
Analyses of St. Clair and Polk Bayou limestones. 
Silica (Si0 2 ) 
Iron oxide ( Fe 2 3 ) 
Alumina (A1 2 3 ) 
Lime(CaO) 
Magnesia (MgO) 
Potash (K 2 0)...-! 
Soda (Na 2 0) 
Loss on ignition (C0 2 , etc.) 
Total 
Water at 110°-115° 
Carbonate of lime (CaC0 3 ). 
Brooks 
mine. 
Hell 
Creek. 
St. Joe. 
St. Clair 
Springs. 
0.73 
0.32 
0.11 
0.54 
.11 
.30 
.08 
.19 
.24 
.10 
.18 
54.82 
55. 74 
56.22 
54. 70 
.24 
Trace. 
Trace. 
j 
.01 
.17 
.07 
.78 
.48 
.22 
.08 
J 
43.08 
43. 31 
43. 79 
43. 35 
99.86 
100. 65 
100. 31 
100. 00 
.09 
.059 
.04 
.04 
97.88 
98.40 
99.68 
97.77 
Lower 
Polk 
Bayou. 
43.39 
100. 28 
98.42 
ST. JOE LIMESTONE. 
DISTRIBUTION. 
St. Joe marble is the name given by the Arkansas geologists to 
the prominent bed of red limestone which is widely distributed over 
early all the counties of Arkansas north of the Boston Mountains. 
It is so named from the village of St. Joe, in Searcy County, Ark. , 
where there is a typical exposure and where it was first studied by 
the Arkansas geological survey. In the publications of the United 
States Geological Survey this bed is termed the St. Joe limestone 
member of the Boone formation. 
GEOLOGIC POSITION. 
The St. Joe limestone is situated at the base of the Boone chert, of 
hich it forms a part. It is underlain by the Chattanooga shale 
Eureka shale in part of Arkansas survey) where that formation 
ccurs, otherwise by the Sylamore sandstone or by Silurian or Ordo- 
ician rocks. In the eastern part of the marble area of the State it 
verlies the St. Clair limestone, from which it is separated in most 
laces by a thin bed of Devonian shale or sandstone; west and north 
)f the borders of the St. Clair limestone it overlies the St. Peter 
saccharoidal sandstone or the Yellville limestone, with either of which 
n sonic places, in the absence of the Chattanooga shale, it may be in 
iirect contact. 
