We also present pre- to early Holocene 10Be surface-exposure ages from two islands located approximately 80 km downstream of the Pine Island Glacier ice-shelf front to constrain the lateral deglacial history in the Pine Island Bay area.This study provides insight into the significance of local ice sheet variations and suggests that the post-LGM history in the Amundsen Sea sector was characterized by glacial thinning as well as lateral retreat in pre- to early Holocene times....Here we present a suite of 58 cosmogenic exposure ages from 17 last-glacial ice limits in the Rangitata Valley of New Zealand, capturing an extensive record of glacial oscillations between 28-16 ka.
In the central Namib, inselbergs appear to be located in or near areas of Plior Pleistocene incision and badland erosion.
These inselbergs therefore are not the best sites to obtain representative passive margin denudation rates.
We obtained a 21 Ne age of 5.18 " 0.18 Ma from a resistant quartz vein projecting above pediment unaffected by recent incision, the oldest exposure age from the Namib so far.
The pediment surface stretching from the base of the escarpment to the ocean, on average, probably has undergone less than 10 m of surface lowering since the mid Miocene.
area suggest that long-term denudation rates of this passive margin after a period of significant post-rift denudation have been very low, ; 5 mrmy.
Aridity of the Namib Desert is generally assumed to have started with the onset of Benguela upwelling in the SE Atlantic at 10–15 Ma and to have prevailed ever since.In this paper, we review ideas on the geomorphological history of the southwest African passive margin, focusing on the central Namib sector and presenting new evidence on the late Neogene landscape evolution of this region. more In this paper, we review ideas on the geomorphological history of the southwest African passive margin, focusing on the central Namib sector and presenting new evidence on the late Neogene landscape evolution of this region.The hyperarid central Namib Desert occupies the 100–150-km-wide pediment at the foot of the Great Escarpment and forms part of the southwest African passive margin, which formed after breakup in the South Atlantic at around 118 Ma. fission track AFT and cosmogenic isotope studies and numerical models of coupled tectonic-surface processes in the same Ž.Correlation of terrace sediment bodies defining ancient river courses is supported by a sediment provenance study using heavy mineral analyses.Our results generally confirm previous work, adding new insights in the late Neogene landscape evolution of the central Ž. They indicate that denudation rates since at least 5 Ma have been even lower of the order of 0.5–1 mrmy than those calculated by previous studies of inselbergs.The quartz was extracted from the samples and purified using a modified version of the technique introduced by Kohl and Nishiizumi (1992; see also Ivy-Ochs, ...