DIAMONDS IN ARKANSAS MISER AND ROSS 263 



boro, near the confluence of Prairie Creek with Little Missouri 

 River, and is known as the Prairie Creek peridotite area. Several 

 thousand stones, ranging in weight from a small fraction of a carat to 

 40.23 carats, have been found, most of them coming from the Ozark, 

 Mauney, and Arkansas mines. The other exposures of peridotite 

 are all within an area of 1 square mile, about 2 miles northeast of 

 the Prairie Creek locality and 3 miles S. 75° E. of Murfreesboro. 

 Two of these exposures, the Kimberlite and American areas, so named 

 for the Kimberlite and American mines located on them, are in sec. 

 14, T. 8 S., R. 25 W. ; the third, the Black Lick area, is near a locality 

 known as the Black Lick, in the northwest corner of sec. 23, T. 8 S., 

 R. 25 W. The Kimberlite and American areas have been prospected 

 for diamonds and each has produced a small number of stones. The 

 Black Lick area has been prospected less than any of the others and 

 has thus far produced no diamonds. 



These known areas of diamond-bearing peridotite are in the Gulf 

 Coastal Plain, only a few miles south of its northern margin, be- 

 yond which lies the Ouachita Mountain region. The Ouachita re- 

 gion, which is 50 to 60 miles wide, extends from Little Rock, Ark., to 

 Atoka, Okla., a distance of 200 miles. It contains numerous nearly 

 eastward trending ridges, several intermontane basins, and a dis- 

 , sected Piedmont Plateau known as the Athens Plateau, which is 15 

 miles wide, lying between the Coastal Plain and the Ouachita Moun- 

 tains. The surface features and also the geologic structure of this 

 part of Arkansas are therefore very similar to those of the Central 

 and South Atlantic States. The Gulf Coastal Plain, which corre- 

 sponds to the Atlantic Coastal Plain, is bordered on the north by 

 the Athens Plateau, which corresponds to the Piedmont Plateau. 

 North of the Athens Plateau there are closely spaced parallel ridges 

 of the Ouachita Mountains, which correspond in appearance and 

 relative position to the Appalachian Mountains between eastern 

 Pennsylvania and northern Alabama. 



The Kimberlite, American, and Black Lick areas of peridotite are 

 on a deeply channeled plateau that lies east of Little Missouri River. 

 The Prairie Creek area adjoins the bottom lands of Little Missouri 

 River and Prairie Creek. 



The region in which the diamond deposits occur is sparsely popu- 

 lated except in the level or gently rolling upland and valley areas, 

 where most of the tillable land occurs. 



ROCKS ASSOCIATED WITH THE PERIDOTITE 



The rocks associated with the peridotite are sedimentary and 

 are of Carboniferous, Lower Cretaceous, Upper Cretaceous, and 

 Quaternary ages. The Carboniferous rocks are shales and sand- 



