Age of the raised beach ridges at Turakirae Head, Wellington: A reassessment based on new radiocarbon dates

Abstract

Revised ages for the five raised beach ridges at Turakirae Head, based on new radiocarbon dates, indicate that the highest and oldest ridge was uplifted between 5500 and 6500 years b.p., and possibly close to 6000 years b.p. (or c. 4900 b.c.). (Dates given in radiocarbon years, old half-life). Uplift of the second youngest raised beach is thought to have occurred about 450 years b.p., or around 1500 a.D. The two intervening beach ridges, dated only by indirect methods, were probably elevated about 2900-3400 years b.p. (c. 1460 b.c.) and 4600–5400 years b.p. (c. 3700 b.c.). These ages are similar to those estimated by Wellman (1967, 1969). The raised beach ridges at Turakirae lie close to the axis of the Rimutaka Range, which has risen at an average rate of 3.9 m/1000 years over the past 6000–7000 years. Based on the assumption that this rate will continue, the next major (> 2 m) uplift at Turakirae (and, by inference a destructive earthquake in the Wellington area) could be in about 800 years time, although smaller (< 1-2 m) uplifts may occur before then.