Geoscience and Environment

Topographic evidence for Quaternary sea-level change

Ara Valley, Penang Island, Malaysia

Aims of the Project

This study develops a model for predicting the elevation of marine terraces associated with sea-level change and coastlines formed during the last million years. Fieldwork aims to acquire photographs, spot elevations and coordinate data using precision barometric altimeters and GPS receivers. The study prepares vertical profiles from digital elevation models (DEMs) derived from topographic maps and satellite images. The test of the predictive model uses breakpoints in slope observed in the profiles.

Statement of Problem

Terraces may form as a result of the combined effects of uplift, sea-level change, and land surface processes. "The coral reef terraces at Huon Peninsula in Papua New Guinea extend more than 80 km along the coast and have been uplifted at a rate that varies from 0.5 m per 1000 years (ky) in the northwest to nearly 4 m/ky to the southeast," (Esat et al, 1999). See photo: Huon Peninsula.

Unlike the Huon Peninsula, Peninsular Malaysia is a stable craton with a rate of uplift, in the order of about twenty meters per million years (Tjia, 1992). Previous studies have indicated that worldwide sea level during the last million years has been at times more than 20 meters higher than now, implying that coastlines were relatively higher (Kaufman and Brigham-Gette, 1993; Kindler and Hearty, 1995).

Thai-Malay Peninsula
Previous research
Studyarea
Fieldwork
Results and discussion
References
Where a region such as Peninsular Malaysia has a tropical climate, erosion and other surface processes remove much of the evidence of past landscapes, including soil and rock as well as plant and animal remains. Do vestiges of ancient coastlines persist in granite subject to a slow rate of uplift? Do medium-resolution digital elevation models (DEMs) reveal breakpoints in slope related to ancient coastlines? This project aims to study these questions. By examining cycles thousands of years long during the Pleisotocene and Pliocene Epochs this study puts sea-level change into a different perspective from the short-term approach that has recently become popular. (For the geological time scale see: Geological periods and USGS).

Research Strategy

My research strategy is to construct a model to predict the location of sea level high stands at selected time periods within a small area of Penang Island. During field visits I will try to observe and photograph features indicative of ancient coastlines.

This methodology may suggest directions for future research but is not capable of providing definitive results because the rate and amounts of uplift are not precise and the influence of changing climate on erosional processes is unknown.

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