Maps of Pleistocene sea levels in Southeast Asia: shorelines, river systems and time durations

Abstract

Aim Glaciation and deglaciation and the accompanying lowering and rising of sea levels during the late Pleistocene are known to have greatly affected land mass configurations in Southeast Asia. The objective of this report is to provide a series of maps that estimate the areas of exposed land in the Indo‐Australian region during periods of the Pleistocene when sea levels were below present day levels. Location The maps presented here cover tropical Southeast Asia and Austral‐Asia. The east–west coverage extends 8000 km from Australia to Sri Lanka. The north–south coverage extends 5000 km from Taiwan to Australia. Methods Present‐day bathymetric depth contours were used to estimate past shore lines and the locations of the major drowned river systems of the Sunda and Sahul shelves. The timing of sea level changes associated with glaciation over the past 250,000 years was taken from multiple sources that, in some cases, account for tectonic uplift and subsidence during the period in question. Results This report provides a series of maps that estimate the areas of exposed land in the Indo‐Australian region during periods of 17,000, 150,000 and 250,000 years before present. The ancient shorelines are based on present day depth contours of 10, 20, 30, 40, 50, 75, 100 and 120 m. On the maps depicting shorelines at 75, 100 and 120 m below present levels the major Pleistocene river systems of the Sunda and Sahul shelves are depicted. Estimates of the number of major sea level fluctuation events and the duration of time that sea levels were at or below the illustrated level are provided. Main conclusions Previous reconstructions of sea‐level change during the Pleistocene have emphasized the maximum lows. The perspective provided here emphasizes that sea levels were at their maximum lows for relatively short periods of time but were at or below intermediate levels (e.g. at or below 40 m below present‐day levels) for more than half of each of the time periods considered.

Convergence of multiple markers and analysis methods defines the genetic distinctiveness of cryptic pitvipers

“…However, it is important 597 to consider the context at the time these species were evolving. The Gulf of Thailand has a 598 maximum depth of 80m, and Voris (2000) showed that for c. (Fig. 5a, b, & c and Fig.…”

Speciation dynamics in the SE Asian tropics: Putting a time perspective on the phylogeny and biogeography of Sundaland tree squirrels, Sundasciurus

“…Lighter color land areas are more than 1000 m above sea level. The black lines show the maximum exposure of land during the Last Glacial Maximum (LGM) around 18,000 years ago when sea levels were 120 m below their current level (after Voris, 2000). The dashed line shows the contour line of exposed land when sea levels were around 40 m below current.…”

“…These connections lasted for tens of thousands of years, and the islands last became isolated only 10,000-12,000 years ago when sea level rose to less than 50 m below present levels (Voris, 2000;Hanebuth et al, 2000). Sea level remained below À50 m for approximately 40% of the time in the last 250,000 years (Voris, 2000), so the islands were not nearly as isolated from one another and the mainland as they are at present.…”

Human genetics of the Kula Ring: Y-chromosome and mitochondrial DNA variation in the Massim of Papua New Guinea

“…25 Archeological findings in the Massim are scant 26 and there is currently no evidence of long-term human occupation before 2 kya. 27,28 Given the lower sea levels during the Pleistocene, many of the current Massim islands may have been connected by land bridges, 29 potentially facilitating human migration between them. The languages spoken in the Massim belong to the Papuan Tip cluster within the Western Oceanic branch of the Austronesian language family, 30 with the exception of Rossel Island, the easternmost island of the Louisiade Archipelago, where a non-Austronesian (Papuan) language is spoken.…”