OSL and TL dating of the Middle Stone Age sequence at Diepkloof Rock Shelter (South Africa): a clarification

Diepkloof Rock Shelter offers an exceptional opportunity to study the onset and evolution of both Still Bay (SB) and Howiesons Poort (HP) techno-complexes. However, previous age estimates based on luminescence dating of burnt quartzites (Tribolo et al., 2009) and of sediments (Jacobs et al., 2008) were not in agreement. Here, we present new luminescence ages for 17 rock samples (equivalent dose estimated with a SAR-ITL protocol instead of classical MAAD-TL) as well as for 5 sediment samples (equivalent dose estimated with SAR-single grain OSL protocol) and an update of the 22 previous age estimates for burnt lithics (modified calibration and beta dose estimates). While a good agreement between the rock and sediment ages is obtained, these estimates are still significantly older than those reported by Jacobs et al. (2008). After our own analyses of the sediment from Diepkloof, it is suspected that these authors did not correctly chose the parameters for the equivalent dose determination, leading to an underestimate of the equivalent doses, and thus of the ages. From bottom to top, the mean ages are 100 ± 10 ka for stratigraphic unit (SU) Noël and 107 ± 11 ka for SU Mark (uncharacterized Lower MSA), 100 ± 10 ka for SU Lynn-Leo (Pre-SB type Lynn), 109 ± 10 ka for SUs Kim-Larry (SB), 105 ± 10 ka for SUs Kerry-Kate and 109 ± 10 ka for SU Jess (Early HP), 89 ± 8 ka for SU Jude (MSA type Jack), 77 ± 8 ka for SU John, 85 ± 9 ka for SU Fox, 83 ± 8 ka for SU Fred and 65 ± 8 ka for SU OB5 (Intermediate HP), 52 ± 5 ka for SUs OB2-4 (Late HP). This chronology, together with the technological analyses, greatly modifies the current chrono-cultural model regarding the SB and the HP and has important archaeological implications. Indeed, SB and HP no longer appear as short-lived techno-complexes with synchronous appearances for each and restricted to Oxygen Isotopic Stage (OIS) 4 across South Africa, as suggested by Jacobs et al. (2008, 2012). Rather, the sequence of Diepkloof supports a long chronology model with an early appearance of both SB and HP in the first half of OIS 5 and a long duration of the HP into OIS 3. These new dates imply that different technological traditions coexisted during OIS 5 and 4 in southern Africa and that SB and HP can no longer be considered as horizon markers.

Water versus ice: The competing roles of modern climate and Pleistocene glacial erosion in the Central Alps of Switzerland

Recent studies have identified relationships between landscape form, erosion and climate in regions of landscape rejuvenation, associated with increased denudation. Most of these landscapes are located in non-glaciated mountain ranges and are characterized by transient geomorphic features. The landscapes of the Swiss Alps are likewise in a transient geomorphic state as seen by multiple knickzones. In this mountain belt, the transient state has been related to erosional effects during the Late Glacial Maximum (LGM). Here, we focus on the catchment scale and categorize hillslopes based on erosional mechanisms, landscape form and landcover. We then explore relationships of these variables to precipitation and extent of LGM glaciers to disentangle modern versus palaeo controls on the modern shape of the Alpine landscape. We find that in grasslands, the downslope flux of material mainly involves unconsolidated material through hillslope creep, testifying a transport-limited erosional regime. Alternatively, strength-limited hillslopes, where erosion is driven by bedrock failure, are covered by forests and/or expose bedrock, and they display oversteepened hillslopes and channels. There, hillslope gradients and relief are more closely correlated with LGM ice occurrence than with precipitation or the erodibility of the underlying bedrock. We relate the spatial occurrence of the transport- and strength-limited process domains to the erosive effects of LGM glaciers. In particular, strength-limited, rock dominated basins are situated above the equilibrium line altitude (ELA) of the LGM, reflecting the ability of glaciers to scour the landscape beyond threshold slope conditions. In contrast, transport-limited, soil-mantled landscapes are common below the ELA. Hillslopes covered by forests occupy the elevations around the ELA and are constrained by the tree line. We conclude that the current erosional forces at work in the Central Alps are still responding to LGM glaciation, and that the modern climate has not yet impacted on the modern landscape.

News from an Old Excavation: Two Hitherto Unnoticed Measure Capacity Signs on an Egyptian Stone Vessel of the Middle Kingdom from Royal Tomb II at Byblos

Excavated by French Egyptologist P. Montet in the 1920s, Royal Tomb II at Byblos (Bronze Age Gubla) yielded a significant number of Egyptian objects of the Middle Kingdom. Among these finds is a stone vessel with lid that carries the cartouche of a king named Amenemhat, often believed to be Amenemhat IV of the late Middle Kingdom. Hitherto unnoticed by the scholarly community, however, are two Egyptian measure capacity signs on the stone vessel itself. Since measure capacity signs on stone vessels dating to the Middle Kingdom are only rarely attested even in Egypt, the signs on the stone vessel from Royal Tomb II at Byblos therefore contribute considerably to our understanding of the use and application of such signs. The article deals with the examination of these signs and tries to correlate them with the actual capacity of the vessel.

Outcome of patients with occlusions of the internal carotid artery or the main stem of the middle cerebral artery with NIHSS score of less than 5: comparison between thrombolysed and non-thrombolysed patients

BACKGROUND AND PURPOSE The use of thrombolysis in patients with minor neurological deficits and large vessel occlusion is controversial. METHODS We compared the outcome of patients with low National Institutes of Health Stroke Scale (NIHSS) scores and large vessel occlusions between thrombolysed and non-thrombolysed patients. RESULTS 88 (1.7%) of 5312 consecutive patients with acute (within 24 h) ischaemic stroke had occlusions of the internal carotid or the main stem of the middle cerebral artery and baseline NIHSS scores ≤5.47 (53.4%) were treated without thrombolysis, and 41 (46.6%) received intravenous thrombolysis, endovascular therapy or both. Successful recanalisation on MR or CT angiography at 24 h was more often observed in thrombolysed than in non-thrombolysed patients (78.9% versus 10.5%; p<0.001). Neurological deterioration (increase of NIHSS score ≥1 compared to baseline) was observed in 22.7% of non-thrombolysed versus 10.3% of thrombolysed after 24 h (p=0.002), in 33.3% versus 12.5% at hospital discharge (p=0.015) and in 41.4% versus 15% at 3 months (p<0.001). Symptomatic intracerebral haemorrhage occurred in two (asymptomatic in five) thrombolysed and in none (asymptomatic in three) non-thrombolysed. Thrombolysis was an independent predictor of favourable outcome (p=0.030) but not survival (p=0.606) at 3 months. CONCLUSIONS Non-thrombolysed patients with mild deficits and large vessel occlusion deteriorated significantly more often within 3 months than thrombolysed patients. Symptomatic intracerebral haemorrhages occurred in less than 5% of patients in both groups. These data suggest that thrombolysis is safe and effective in these patients. Therefore, randomised trials in patients with large vessel occlusions and mild or rapidly improving symptoms are needed.