Type of Earthcache: Sea Level Change/Fossil Site/Cave Feature.
Sea Level Change: Peninsular Malaysia & Sunda Shelf in South-East Asia
Haile (1971, 1975) pointed out that much of the evidence quoted to support high Pleistocene (2.58 million years to 12,000 years ago) sea levels does not stand up to critical examination in so far as Peninsular Malaysia was concerned and concluded that there was no compelling evidence for Quaternary (2.58 million years to present-day) shorelines above 6 m, and the balance of evidence is against any eustatic (global changes in sea level relative to a fixed point, such as the centre of the earth) sea level higher than 6 m affecting Peninsular Malaysia in the late Cenozoic (Raj et al., 2009).
Hanebuth et al. (2000) presented a sea level curve for the Sunda Shelf based on more than 50 sediment cores. The rise in sea level is attributed wholly to continued episodic melting of the ice caps resulting in increasing quantities of water in the seas. The late to post-glacial sea-level curve for the Sunda Shelf is shown in Figure 1.
Figure 1: Sea level curve for the Sunda Shelf derived from shoreline facies of cored samples, redrawn after Hanebuth et al. (2000). The dashed part was complied by Wan Hasiah Abdullah with Kamaludin (2004).
The deglaciation has resulted in rising of the sea levels during the Late Pleistocene (21,000 to 12,000 years ago) and has greatly affected the area of exposed land in South-East Asia. Sathiamurthy and Voris (2006) have presented a series of maps for Pleistocene coastlines over the past 21,000 years before present. Figure 2 shows the coastline map for 21,000 years ago when the sea level was -116 m below present-day sea level whereas Figure 3 shows the coastline map for 4,200 years ago when the sea level was +5 m above present-day sea level. Figure 4 shows the present-day coastline.
Figure 2: Coastline map for 21,000 years ago when the sea level was -116 m below present-day sea level.
(Source: Sathiamurthy and Voris, 2006)
Figure 3: Coastline map for 4,200 years ago when the sea level was +5 m above present-day sea level.
(Source: Sathiamurthy and Voris, 2006)
Figure 4: Present-day coastline map.
(Source: Sathiamurthy and Voris, 2006)
These maps indicate that the Sunda Shelf is extensively a product of the Quaternary (2.58 million years to present-day) ice age and the deglaciation that followed (Hutchison, 2009).
Based on available published information, it is clear that high sea levels (>6 m above present-day) during the Quaternary (2.58 million years to present-day) did not influence Peninsular Malaysia, yet field evidences show otherwise as in the case of fossiliferous beds of Anadara granosa (blood cockle) found in a cave at Bukit Papan.
Regional Geology of Bukit Papan
Bukit Papan (Papan Hill) is a limestone hill at Kuala Perlis, Perlis, Malaysia. Jones, 1981 identified Bukit Papan as Lower Setul Limestone of Middle to Upper Ordovician age (472 to 444 million years ago). The Lower Setul Limestone is part of the Setul Formation of Ordovician to Silurian age (488 to 416 million years ago). Later, Cocks et al., 2005 reclassified the Lower Setul Limestone as Kaki Bukit Limestone that is thickly bedded (1037 m thick) dark grey limestone with sporadic horizons rich in shelly fossils and others in which organic remains are scarce. The rock is typically indurated (hardened) with segregation of impurities into styolites (banded structures in some marbles) and irregular laminae and bodies that are often silicified, producing a prominent banded aspect. Figure 5 and Figure 6 show the regional geology map and geological cross section (published in 1967) of Bukit Papan.
The Upper Cambrian to Lower Ordovician (499 to 472 million years ago) Machinchang Formation that conformably underlain the Kaki Bukit Limestone is not exposed in the Bukit Papan area.
Unconformably overlying the Kaki Bukit Limestone is the Holocene age (10, 000 to 0 years ago) alluvium, identified as Gula Formation which consists of estuarine to marine sediments of sand, silt and clay (Suntharalingam, 1983). Much of the region around Bukit Papan is covered with this alluvium (Figure 5).
Figure 5: Regional geology of Bukit Papan.
(Source: Geological Survey, West Malaysia, 1967a)
Figure 6: Geological section (C-C1) across Bukit Papan.
(Source: Geological Survey, West Malaysia, 1967b)
Fossil: Anadara granosa (blood cockle)
Anadara granosa, as shown in Figure 7, is a species of ark clam known as the blood cockle due to the red haemoglobin liquid inside (Blood cockle, 2012). Ark clam is the common name for a family of small to large-sized saltwater clams or marine bivalve molluscs in the family Arcidae (Ark clam, 2012). Anadara granosa is found throughout the Indo-Pacific region from eastern Africa to Australia to Polynesia to Japan. It lives mainly at 1 to 2 metres water depth, burrowed down into sand or mud. Adult size is about 5 to 6 cm long and 4 to 5 cm wide. The mantle (a significant part of the anatomy of molluscs) has three apertures (inhalant, exhalant, and pedal) for siphoning water and for the foot to protrude. It typically burrow using the foot, and feed by filtering plankton from the surrounding water.
Figure 7: Anadara granosa (blood cockle) in the fossiliferous beds of the cave in Bukit Papan.
Cave features of Bukit Papan
The cave consists of the floor (ground you walk on), the walls, the ceiling, stalagmites (structures that rise from the floor of the cave), stalactites (structures that hang from the ceiling of the cave), and columns (structures that stretch from the floor to the ceiling of the cave).
How to claim this EarthCache?
Field equipment required:
1. A 5-meter measuring tape.
2. Torch light.
From the listed coordinates, walk into the cave and look for fossiliferous beds (indurated greyish yellow brown mud layer) of Anadara granosa
Send me the following via the Geocaching Message Centre;
1. The text "Bukit Papan - Sea Level Change" on the first line.
2. The answers to the following questions;
- In which part of the cave are the fossiliferous layers of Anadara granosa attached to?
- Given that the floor of the cave is 22 m above the current sea level, what is the maximum sea level at the time the fossiliferous layers were deposited? Explain your answer.
- Radiometric dating of the Anadara granosa was not done. From information in the listing, estimate how long ago were these fossiliferous layers deposited. Explain your answer.
- How far away (in kilometres) from the present-day coastline are the fossiliferous layers? This question gives you an idea of how far the sea had transgressed inland (sea level rose relative to the land and the shoreline moves toward higher ground, resulting in flooding) at Bukit Papan.
3. Optional task: Share your experiences and photos taken during your visit.*
References
1 Ark clam, 2012. Available from http://en.wikipedia.org/wiki/Arcidae [Accessed on 29 April 2012]. 2 Blood cockle, 2012. Available from http://en.wikipedia.org/wiki/Anadara_granosa [Accessed on 29 April 2012]. 3 Cocks, L.R.M., Fortey, R.A. & Lee, C.P., 2005. A review of Lower and Middle Palaeozoic biostratigraphy in west Peninsular Malaysia and southern Thailand in its context within the Sibumasu Terrane. Journal of Asian Earth Sciences, 24, 703-717. 4 Geological Survey, West Malaysia, 1967a. Geological map of Perlis/Kedah – Sheet 2E/9 Kangar. 5 Geological Survey, West Malaysia, 1967b. Geological sections across sheets 2E/5, 2E/6, 2E/9 & 2E/10. 6 Haile, N.S., 1971. Quaternary shorelines in West Malaysia and adjacent parts of the Sunda Shelf. Quaternaria, V.XV, 333-343. 7 Haile, N.S., 1975. Postulated Late Cainozoic high sea-levels. Journal Malaysian Branch Royal Asiatic Society, 48, 78-88. 8 Hanebuth, T., Stattegger, K. & Grootes, P.M., 2000. Rapid flooding of the Sunda Shelf: a late glacial sea-level record. Science, 288, 1033-1035. 9 Hutchison, C.S., 2009. Regional geological setting. In: Hutchison, C.S. & Tan, D.N.K. (eds.), 2009. Geology of Peninsular Malaysia. UM & GSM, Kuala Lumpur, Malaysia, pp 40-41. 10 Jones, C.R., 1981. The Geology and Mineral Resources of Perlis, North Kedah and the Langkawi Islands. Geological Survey Malaysia District Memoir, 17, 257 p. 11 Kamaludin Hassan, 2004. The postglacial and Holocene periods. In: Nik Hassan Shuhaimi (ed) Early History, The Encyclopaedia of Malaysia, Archipelago Press, 16-17. 12 Raj, J.K., Tan, D.N.K. and Wan Hasiah Abdullah, 2009. Cenozoic Stratigraphy. In: Hutchison, C.S. & Tan, D.N.K. (eds.), 2009. Geology of Peninsular Malaysia. UM & GSM, Kuala Lumpur, Malaysia, pp 172-173. 13 Sathiamurthy, E. and Voris, H. K. 2006. Maps of Holocene Sea Level Transgression and Submerged Lakes on the Sunda Shelf. The Natural History Journal of Chulalongkorn University. Supplement 2:1-43. 14 Suntharalingam, T., 1983. Cenozoic stratigraphy of Peninsular Malaysia. Proceedings of the workshop on stratigraphic correlation of Thailand and Malaysia. Geological Society of Thailand & Geological Society of Malaysia, 149-158.
* It is understood that finding the answers to an EarthCache can be challenging, and many people tend to shy away from these caches because of this. However, it is my opinion that geocaching is also meant to be a fun family experience that simply aims to introduce interesting and unique locations such as this one. Flexibility on logging requirements, however, can only be applied if it can be established that you have actually taken the time to visit the site. For this reason, a proper log describing your adventure accompanied by a good number of photos would be much appreciated.
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