Abstract
Coastal sand dunes are sediment archives which can be used to reconstruct periods of aridity and humidity, past wind strength and variations in the sediment supply related to sea‐level changes. In this manner, the sedimentary record of fossil coastal dunes in Sri Lanka provides evidence for environmental and climatic changes during the late Pleistocene and Holocene. As yet, these environmental shifts are poorly resolved because the sedimentary facies and their depositional architecture have not been studied and only very few age constraints are available. Facies analysis of a lithological section at the Point Kurdimalai sea cliff in the Wilpattu National Park (NW Sri Lanka) reveals a striking resemblance to the stratigraphic succession associated with the Teri Sands in southeastern India, which is better dated. The reason is that deposition occurred under the same geological, climatic and geomorphological conditions in the two regions. This special situation allows for litho‐ and climate stratigraphic correlations across the Gulf of Mannar and links the landscape evolution at Point Kudrimalai to late Quaternary climatic events and sea‐level changes. Our results show that the formation of red coastal dunes (Red Beds) in Sri Lanka was a multi‐phase process across the Pleistocene–Holocene boundary and hence the differentiation between an Older Group of Plio‐Pleistocene age (including the Red Beds) and a Younger Group of Holocene age in the Quaternary stratigraphic chart for Sri Lanka is not justified.
Highlights
Point Kudrimalai (‘Horse Point’) at the northwestern edge of the Wilpattu National Park in Sri Lanka has a fascinatingly bizarre labyrinthic landscape of up to 2-m-high conical sandstone pinnacles covered by deep red sand (Figure 1)
This study shows that Red Bed formation was a multi-phase process across the Pleistocene– Holocene transition (Figure 8), contradicting the general twofold stratigraphy for the Quaternary of Sri Lanka (Katupotha, 1994), which differentiates between an Older Group of Plio-Pleistocene age and a Younger Group of Holocene age
A comparison with the sedimentary succession which is found associated with the Teri Sands in Tamil Nadu (SE India) on the opposite shore of the Gulf of Mannar reveals a strong lithological and environmental similarity that allows for lithostratigraphic correlations on a regional scale
Summary
Point Kudrimalai (‘Horse Point’) at the northwestern edge of the Wilpattu National Park in Sri Lanka has a fascinatingly bizarre labyrinthic landscape of up to 2-m-high conical sandstone pinnacles covered by deep red sand (Figure 1). We describe the lithological sequence at Point Kudrimalai in order to understand the palaeo-environmental changes that led to this peculiar landscape and to place the Red Beds in a stratigraphic context to the Teri Sands and past patterns of climate change in the Indian monsoon region. The studied outcrop is located at the coastal cliff of Point Kudrimalai in the Wilpattu National Park (North Western Province; N 0832019.2300, E 07952021.9800) This place is accessible via a rough track leading at the Malai Villus from the Puttalam-Marichchukkaddi Road to the coast (Figure 2b). Stratigraphic approach including information from lithostratigraphy, altimetry and TL dating is used to resolve environmental changes with the best possible time resolution
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