Several thick deposits of gravel are widely distributed along the north edge of the Gulf Coastal Plain, of which a narrow belt is embraced in the southern parts of the Caddo Gap and De Queen quadrangles, Ark. This belt is shown on Plate I, and its location is shown on figure 5, a key map of this region. It comprises parts of Pike, Howard, and Sevier counties and a narrow strip of Hemp- stead County, in southwestern Arkansas, and a strip along the east edge of McCurtain County, in southeastern Oklahoma. The gravels are of Lower Cretaceous, Upper Cretaceous, and Quaternary age, and are composed mainly of pebbles of novaculite (a variety of chert) derived from the Arkansas novaculite exposed in the Ouachita Mountain region, which is north of the Gulf Coastal Plain. They are used in making concrete, in ballasting railroads, and in the construction of wagon roads. Very small quantities of pebbles are also used in the washing plant of the Kimberlite Diamond Mining & Washing Co., at Murfreesboro, to assist in the disintegration of the altered peridotite which carries the diamonds.
Interest in possible American sources of flint pebbles or substitutes therefor to be used in tube mills, in which minerals, ores, cement materials, and clinker are extensively ground in this country, has been aroused since the beginning of the present world war. This interest is due to the partial interruption of imports of flint pebbles from Denmark and France, which have supplied most of the pebbles used in this country. The main reasons for the preparation of this report are to present a description of the gravels under discussion and to indicate the possibility of their use in tube mills.
The information for this report is the result of detailed field studies in the Caddo Gap and De Queen quadrangles by the authors in 1908 and 1911 and by the senior author in 1912 and 1916. Mr. E, D. Mesler rendered valuable assistance in 1912. Much of the information is abstracted from the De Queen-Caddo Gap folio, which is nearing completion.
