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U–Pb SHRIMP ages are reported for three rhyolite flows from the Lebombo rift region of the Karoo volcanic province. Two flows are interbedded with the Sabie River Basalt Formation and a third sample is from the overlying rhyolitic Jozini Formation. The interbedded rhyolites yield ages of 182.0 ± 2.1 and 179.9 ± 1.8 Ma, whilst the overlying Jozini Formation rhyolite yields an age of 182.1 ± 2.9 Ma. Combined with existing 40 Ar/ 39 Ar geochronology, the new SHRIMP data fine-tunes the chronology of the Karoo volcanic province and indicates the 12 km succession of volcanic rocks in the Lebombo rift were erupted in 1–2 million years and lends considerable support to the links between the Pleinsbachian–Toarcian extinction event and the global environmental impact of Karoo volcanism.

Two accelerator mass spectrometry (AMS) dates obtained from samples of Zea mays from the Holding site, 11MS118, in the American Bottom near East St. Louis, Illinois, establish the presence of maize in the Mississippi Valley between 170 B.C. and A.D. 60. The dates finally establish the occurrence of Middle Woodland maize in Illinois and are the earliest dates thus far for maize east of the Mississippi River. Other reports of early Middle Woodland maize in the Midcontinent region should not be discounted unless AMS dating and other supporting information show the maize to be a contaminant at the site at which it occurs. Recent stable carbon-isotope experiments suggest that the relative contribution of maize to Middle Woodland diets is still an open question.

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