ScienceAsia 49 (2023): 353-360 |doi:
Beach ridge evolution in response to the Holocene sea-level
change from Surat Thani, Thai-Malay Peninsula
Sinenard Polwichaia, Sumet Phantuwongrajb, Montri Choowongb,*
ABSTRACT: Sets of beach ridge plains and sand spit at Laem Pho, Chaiya coast of Surat Thani, the Thai-Malay peninsula,
the Gulf of Thailand show their evolution in response to a long-term sea-level change from the middle Holocene to the
present. The most landward set of beach ridges defines the paleo-shoreline located at 4.5 km far inland with an elevation
up to 4 m of ancient sea level above the present mean sea level. Interestingly, the orientation of beach ridges reflects
that they were mainly formed by longshore current in southeast direction likely similar to beach ridges in the other
coastal sectors of the western part of the Gulf. The major composition of beach ridge included quartz, whereas minor
composition was feldspar. Roundness and sphericity of beach ridge sediments showed sub-rounded and sub-angular.
Physical properties of beach sediment and the preservation of feldspar in beach sediment suggest the main source from
granite exposure near this coastal plain. Major sediment pathway was possibly supplied from the Phum Rieng canal.
Optically stimulated luminescence dating revealed the formation of beach ridge plain here starting from 7,171?460
years BP. The sand spit has been formed at 440 years BP. These ages responded to the formation of beach ridge after
sea level had reached the highstand in the middle Holocene.
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||Inter-Department of Environmental Science, Graduate School, Chulalongkorn University, Bangkok 10330 Thailand
||Center of Excellence for the Morphology of Earth Surface and Advanced Geohazards in Southeast Asia (MESA CE),
Department of Geology, Faculty of Science, Chulalongkorn University, Bangkok 10330 Thailand
* Corresponding author, E-mail: firstname.lastname@example.org
Received 19 Aug 2022, Accepted 26 Jan 2023