Smooth or oscillating late Holocene sea-level curve? Evidence from cross-regional statistical regressions of fixed biological indicators

• Published in: Marine geology 2000-02, Vol.163 (1), p.353-365
• Main Authors: Baker, R.G.V, Haworth, R.J
• Format: Article
• Language: English
• Subjects: Holocene; intertidal fossils; Marine; regression curves; sea-level change; Southern Hemisphere
• ISSN: 0025-3227; 1872-6151
• DOI: 10.1016/S0025-3227(99)00117-6

What, if any, is the pattern of change of the late Holocene sea-level curve? If a common pattern exists, can it be better discerned in the non-glaciated, tectonically stable regions of the Southern Hemisphere? And is sea level data more reliable from one type of marine sample than another? To begin an investigation of these questions, we present a review of regressing time–elevation plots from the low to mid latitudes of the Southern Hemisphere based upon the differential between modern and past levels of various fixed biological indicators (mainly calcareous tubeworms and corals) stranded up to ∼2 m above present relative sea levels. The sample sets come from our work in southeast Australia and comparable work from north-east Australia, the Pacific Islands and Brazil. We show that, using evidence obtained from fixed intertidal tubeworm species, there is no statistical exclusivity between the smooth and oscillating polynomials, but corals are more problematic. In situ tubeworm species with their reduced error bars in comparison to corals fulfil the condition of providing more robust results for statistical analysis. Regression curves based on these species point to cross-regional similarities in the pattern of sea-level movement of the last 6000 years across the lower latitudes of the Southern Hemisphere. These statistical exercises, while not able to yield definitive conclusions, can highlight statistically equally likely alternative patterns of sea-level movement which can then be tested by field evidence. They can also give useful indications of the quality of sea-level data obtained from different biological sources, as in the difficulties in the use of corals compared to common intertidal tubeworm species.