Pg. 125. Hatton tuff lentil of Stanley shale. Tuff of Carboniferous age occurs near base of Stanley shale in Ouachita Mountain region in Polk County, Arkansas, and McCurtain County, Oklahoma. There are 3, and possibly 4 or 5, beds of it, ranging in thickness from 6 to 85 feet. All of them are very similar in lithologic character. Lowest bed is thickest and most widely distributed. The tuffs are compact, massive, and tough; generally homogeneous except for presence of numerous chloritic pellets that lie parallel with bedding; of dark-gray color with a greenish tinge. None of tuffs have yielded fossils, and their assignment to Mississippian is based on relations of Stanley shale to overlying and underlying rocks, whose age has been determined by fossils.
Has been mapped in detail in DeQueen quadrangle, lying mostly in Arkansas, and to it name Hatton tuff lentil has been applied, for reason the best known exposure is in a cut of Kansas City Southern RR 0.5 mi south of Hatton [Polk Co., AR].
[GNC remark (ca. 1938, US geologic names lexicon, USGS Bull. 896, p. 924, 2053): In DeQueen quadrangle, southwestern AR, [Hatton tuff lentil] lies 500+/- feet above base of Stanley shale. Age changed to Pennsylvanian in 1934. See H.D. Miser, 1934, AAPG Bull., v. 18, no. 8. [available online, with subscription, from AAPG archives: http://www.aapg.org/datasystems or http://search.datapages.com].]

Source: US geologic names lexicon (USGS Bull. 896, p. 924).

Pg. 1582. Paleontological evidence [conodonts] suggests that the Hatton tuff is Meramec in age.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1703).