Robert H. Rutford, Department of Geosciences, University of Texas at Dallas, 800 West Cambell, Richardson, TX 75080 and William C. McIntosh, Department of Earth and Environmental Sciences, New Mexico Tech, 801 Leroy Pl, Socorro, NM 87801.
The Jones Mountains, Antarctica, were first sighted in January, 1960. In late 1960 they were visited by a team led by Cam Craddock. The mountains consist of a Mesozoic basement complex truncated by a major erosion surface which is overlain by a sequence of basaltic volcanoclastics. The erosion surface is striated and grooved, and immediately above the surface is a tillite (diamictite) with a matrix of palagonite and containing exotic clasts of rock types unknown locally. Examination of the surface and the overlying basal unit of the volcanics led to the conclusion that this represented a subglacial eruption. Age determinations on the basalts initially were difficult to interpret. Samples collected more systematically in 1968-69 indicated an age of 7-10 Ma. More recent duplicate Ar/Ar ages on these samples provide support for the Miocene age assigned to the glaciation.
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