Laem Pho Mollusc Fossil, Krabi
Mollusc fussil site are exposed at Laem Pho, Tambon Sai Thai, Muang District, Krabi Province, in the vicinity of Hat Noppharat Thara Mu Ko Phi Phi National Park.
Laem Pho site 1
Located West of visitor center, crops out as a rock beach and can be clearly seen during miximum low tide. The pan shaped outcrop is resulted from sinking of underlying claystone beds. The fossil bed consists of stubby shaped gastropods (Family Viviparidae) ranging in size 1-2 cm.
Laem Pho site 2
Located at visitor centre is exposed as a 1-2 m think limestone bed. This limestone bed contains millions of compacted gastropods and is underlain by 20-40 cm. thick lignite and claystone beds. These beds are easily eroded by wave actions resulting in collapsing of gastropod beds.
Laem Pho site 3
Located approximately 1,000 m. east of visitor centre. The site can be accessed along the track during low tide. Mollusc beds at this site are approximately 3 m. thick, consisting of gastropods and bivalves. However, gastropod fossils from this site range in size from 1-2 cm. with study and long shaped forms, respectively long shaped gastropods are found only at Laem Pho site 3
Credit : Department of Mineral Resources sign board
75 million years shell cemetery
Is a form of limestone layers measured at full tide about 200 meters long 50 meters wide. It is composed of dead shells known in geology as “Fossil”. Most of these dead shells are of the species of snails, round in shafe, about 2 cm. long. The shells have piled up on top of one another and were cemented together by silicic matter, which turned the pile into a structure of rock about 40 cm. thick. The layer of rock below it became a type of coal called Lignite, and is about 10 cm. thick. Below the Lignite is a layer of shale. The nature of the rock and its formation it is possible to calculate that it way formed about 75 million year ago. During that period the region of the Ban Laem Pho used to be swamp area, with a mass of dead foliage consolidated into a type of coal called lignite. In later periods many species of shells appeared and occupied the swamp, breeding into millions, it would appear that occupied the swamp, breeding into millions, it would appear that certain change occurred in this region later, and the swamp area was submerged in the sea water killing the shell population. Silicic matter form the sea water cemented them together forming a structure of rock. Another evolution developed on the earth pushing portions of this rock formation above the sea level, hence the present phenomenon occurred. Accouring to available information there are only three of this type of shell cemeteries in the world on in The State of Chicago, U.S.A., one in Japan and this one in Ban Laempomin, Thailand.
Strata at these three sites are interpreted as having been deposited in fresh water lakes during 35 million years ago. Depositional events are summarized as follows
1. Sediments were accumulated into the basins as clay mixed with plant remains and gastropod fragments. This indicates the presence of plants and animals in the lakes.
2. Plant remains were then accumulated upon clay layers and became peat and lignite.
3. In the final stage, clayey sediments were mixed with calcareous components and abundant shell fragments. This is due to huge population of gastropods living in fresh water lakes. Changes in paleoenvironments and fluctuations of water level resulted in increasing and decreaising numbers of gastropod population as recorded in fossil beds.
4. The presence of laterie, lateritic soil, river and beach sands. Overlying molluse beds indicates that fresh water lakes became a landmass prior to 200,000 years.
Credit : Laem Pho Molluse Fossil sign board
