Abstract U–Pb ages of detrital ( n = 2391) and magmatic ( n = 170) zircon grains from the Harz Mountains were obtained by LA-ICP-MS for provenance studies and absolute age dating. Results point to a complete closure of the Rheic Ocean at c. 419 Ma. A narrow Rhenish Seaway then re-opened in Emsian to mid-Devonian time ( c. 390–400 Ma). Devonian sedimentary rocks of the Harz Mountains were deposited on the northwestern (Rheno-Hercynian) and on the southeastern (Saxo-Thuringian) margins of the Rhenish Seaway. A new U–Pb zircon age from a plagiogranite (329 ± 2 Ma) within a harzburgite makes the existence of oceanic lithosphere in the Rhenish Seaway probable. The Rhenish Seaway was completely closed by Serpukhovian time ( c. 328 Ma). Existence of a terrane in the seaway is not supported by the new data. Provenance studies and spatial arrangement allow reconstruction of the thin- to thick-skinned obduction style of the Harz Mountains onto the southeastern margin of East Avalonia (Rheno-Hercynian Zone) during the Variscan orogeny. Detrital zircon populations define Rheno-Hercynian and Saxo-Thuringian nappes. Intrusion of the granitoid plutons of the Harz Mountains occurred in a time window of c. 300 to 295 Myr and constrained the termination of Variscan deformation.

ABSTRACT Field work during the past 70 years have established numerous mammoth sites on three of the Northern Channel Islands. Most of these sites have yielded bone remains of the pygmy mammoth Mammuthus exilis . In 1985 and 1987, three sites on the northwestern side of San Miguel Island yielded, from late Pleistocene eolianite sandstones, a complete right hind leg, a complete jaw, and a partial skull with molars. Measurements on the bones confirm that all three sites contain the pygmy mammoth. Molars in the jaw are M6 suggesting a 46 (AEY) year-old mammoth, and the molars in the skull are M4 suggesting a 15 (AEY) year-old mammoth. No radiocarbon dates are available for these three sites, but a recently discovered skull in an eolianite sandstone on San Miguel Island has been dated at approximately 41,000 years B.P.