Post-St. Peter Ordovician strata in the vicinity of Allison, Stone County, Arkansas

Abstract Exposed at Allison are the Ordovician St. Peter Sandstone, Joachim Dolomite, Plattin, Kimmswick, and Fernvale Limestones, and Cason Shale, as well as the Mississippian Boone Formation. A geologic map of the vicinity of Allison is in McFarland and others (1979). The Allison section, along with related exposures, is included in Craig and others (1984). The outcrop consists of two obvious, closely spaced roadcuts, referred to by local geologists as Allison South and Allison West (Fig. 1). Allison South is on Arkansas 9, approximately 4 mi (6 km) north of Mountain View. Allison West is on Arkansas 14, approximately 0.5 mi (0.8 km) west of its junction with Arkansas 9, between the small community of Allison and the entrance to Blanchard Spring Caverns. The roadcuts are in Sec. 14 and 10, T.15N., R.11W. of the Sylamore and Fifty Six 7½-minute Quadrangles, respectively. Both Allison localities are easily accessible. Neither Arkansas 9 nor 14 is heavily traveled. Ample shoulder space makes these locations ideal for relatively large groups. Parking at Allison South is better on the shoulder west of the highway. A turnout opposite Allison West allows convenient parking there. Allison South provides a nearly complete exposure from uppermost St. Peter Sandstone through Plattin Limestone. Higher rocks are better viewed at Allison West, which exhibits a complete section from uppermost Plattin into the lower part of the Boone Formation.