Named as middle member (of 3) of Fort Scott limestone of Marmaton group in southeastern KS. Probably named for the Little Osage River. Type exposure is in the northeast part of the SE1/4 sec 2, T24S, R25E, Bourbon Co, KS in the Cherokee basin. Description of the 12 ft thick measured section at this exposure is given. Consists of the shale, coal bed, and the Houx limestone bed at type. Lies between the Blackjack Creek limestone member (below) and the Higginsville limestone member (above) of Fort Scott limestone of Marmaton group. In KS is about 5 to 11 ft thick. Includes Houx limestone bed near top. Cross section. Of Pennsylvanian, Des Moines age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Assigned as basal formation of Stephens Forest Formation of Marmaton Group of Des Moines Supergroup in Lucas Co, IA on the Iowa shelf. Restricted to rocks above the Summit Coal Member of the newly named Morgan School Shale of Marmaton Group of Des Moines Supergroup and beneath the Houx Limestone Member of Stephens Forest Formation. Name assigned to a 2.5 ft thick black to medium gray silty shale with abundant phosphate nodules. Little Osage formerly included Summit coal and the Houx. Nomenclature chart. Graphic section. Of Pennsylvanian, Desmoinesian age.

Source: GNU records (USGS DDS-6; Denver GNULEX).