A late Pleistocene–Holocene multi‐proxy record of palaeoenvironmental change from Still Bay, southern Cape Coast, South Africa

Lynne J Quick,Arnoud Boom,Paula J Reimer,Brian M Chase,Mark D Bateman,David L Roberts,Michael E Meadows,Andrew S Carr

doi:10.1002/jqs.2825

Abstract

ABSTRACTThe southern Cape is a key focus for southern African palaeoenvironmental research as it represents the transitional region between temperate westerlies and sub‐tropical rainfall sources. This study presents pollen, plant biomarker, geochemical and charcoal data preserved in the Rietvlei wetland. The bulk of the record spans the last 16 ka, but it also provides rare insights into late Marine Oxygen Isotope Stage (MIS) 3 (ca. 35–30k cal a BP). The data suggest that during the Pleistocene the development and permanence of this wetland was probably influenced by sea‐level change via control on the local water table; notably lower sea levels within MIS 2 resulted in very limited wetland productivity. The MIS 3 section provides evidence both supporting previous suggestions of relatively humid conditions, but also some indication of periodic arid phases. The Holocene record suggests clear contrasts between the early (11–7k cal a BP; relatively humid), mid‐Holocene (7–3.3k cal a BP; more arid, less productive wetland conditions) and latest Holocene (last 2k cal a BP; resurgence in both fynbos and aquatic/riparian pollen). While isolating the roles of winter/summer rainfall remains challenging, these data clarify the nature of change during key episodes in the regional palaeoenvironmental record.

Highlights

Air Boundary, ITCZ: Inter Tropical Convergence Zone.The southern Cape coastal lowlands include a significant portion of the Fynbos Biome- the dominant vegetation of the Cape Floristic Region, which is known for its exceptionally high levels of species richness and endemism, elements of the Albany Thicket Biome and rare afrotemperate forest patches (Mucina and Rutherford, 2006; Figure 2)
Through the analysis of sediments from a core extracted at this site, we investigate the relationship between changing rainfall seasonality and vegetation dynamics, including the responses of particular vegetation types to late Quaternary environmental change
Rietvlei-Still Bay 2 (RVSB-2) was split in the laboratory, initially under darkroom conditions to allow sampling for optically stimulated luminescence (OSL) dating

Summary

Introduction

The southern Cape coastal lowlands include a significant portion of the Fynbos Biome. - the dominant vegetation of the Cape Floristic Region, which is known for its exceptionally high levels of species richness and endemism, elements of the Albany Thicket Biome and rare afrotemperate forest patches (Mucina and Rutherford, 2006; Figure 2). Despite their botanical palaeoenvironmental/ecological data pertaining to the history of these coastal lowlands. We report the palaeoenvironmental records preserved in the Rietvlei wetland near to Still Bay on the Riversdale Plain (Figure 2). Through the analysis of sediments from a core extracted at this site, we investigate the relationship between changing rainfall seasonality and vegetation dynamics, including the responses of particular vegetation types (fynbos and non-fynbos communities) to late Quaternary environmental change

Methods

Results

Discussion

Conclusion