Stratigraphic evidence and extensive optically stimulated luminescence (OSL) geochronology from an 18-km-long reach of the middle Rangitata Valley, South Island, New Zealand, provide evidence for at least six distinct glacial advances during the last glacial cycle. These include four well-constrained Marine Oxygen Isotope Stage (MIS) 3 and 2 advances at ca. 38 ka, ca. 27 ka, ca. 21 ka and at 18 ka, as well as less well-constrained advances in MIS 4 and/or early MIS 3. Ice occupied a farther downvalley reach of the Rangitata from 38 ka to after 18 ka, indicating that near-full glacial conditions persisted for most of the last 20 ka of the last glaciation, though the glacier still fluctuated significantly, as reflected by the numerous distinguishable advances. Global or regional cooling alone cannot explain the persistence of near-maximum glacial conditions for this extended period, nor can it explain the occurrence of the largest advances ca. 32 ka. Instead, we invoke the northward expansion of the westerlies during MIS 3 as the cause for the early widespread glaciation, wherein enhanced westerly flow under moderate cooling maximised glacial extents. Local insolation favoured extended MIS 3 glaciation until ca. 32 ka. Increasing summer insolation gradually reduced glacial extents after ca. 28 ka.

Loess accumulated on a Bull Lake outwash terrace of Marine Oxygen Isotope Stage 6 (MIS 6) age in southern Jackson Hole, Wyoming. The 9 m section displays eight intervals of loess deposition (Loess 1 to Loess 8, oldest), each followed by soil development. Our age-depth model is constrained by thermoluminescence, meteoric 10Be accumulation in soils, and cosmogenic 10Be surface exposure ages. We use particle size, geochemical, mineral-magnetic, and clay mineralogical data to interpret loess sources and pedogenesis. Deposition of MIS 6 loess was followed by a tripartite soil/thin loess complex (Soils 8, 7, and 6) apparently reflecting the large climatic oscillations of MIS 5. Soil 8 (MIS 5e) shows the strongest development. Loess 5 accumulated during a glacial interval (~ 76–69 ka; MIS 4) followed by soil development under conditions wetter and probably colder than present. Deposition of thick Loess 3 (~ 43–51 ka, MIS 3) was followed by soil development comparable with that observed in Soil 1. Loess 1 (MIS 2) accumulated during the Pinedale glaciation and was followed by development of Soil 1 under a semiarid climate. This record of alternating loess deposition and soil development is compatible with the history of Yellowstone vegetation and the glacial flour record from the Sierra Nevada.