GEOLOGICAL FORMATION & PALEOENVIROMENT OF THE RAKWANA-PANNILA MOUNTAIN - SRI LANKA

GEOLOGICAL FORMATION & PALEOENVIROMENT OF THE RAKWANA-PANNILA MOUNTAIN - SRI LANKA

Sumanarathna. A.R^1,2,3,  Wijayathunga. W.A.L.K^1,2, Silva E.I.P⁴,  Hathalahawaththa D.K¹,  Fernando G.W.A.R.², Sewwnadi SL² , Silva.A.C²

1. South Asian Astrobiology & Palaeobiology Research Unit of Eco Astronomy Sri Lanka

2. Faculty of Natural Science, The Open University of Sri Lanka, PO Box 21, Nugegoda

3. Postgraduate Institute of Archaeology, University of Kelaniya

4. Faculty of Applied Sciences University of Sri Jayewardenepura,Nugegoda

The Rakwana mountain range, which is located in the margin of the northern side of Sinharaja,UNESCO world heritage site, is an area having rich bio–diversity,included unique geological formations such as limestone caves etc. Numerous fossils of  Elephants(Elephas spp.), Gaur(Bos gaurus), Sambar Deer (Rusa unicolor), Rhinoceros (Rhinoceros kangawena), Red dogs(Cuon sinhaleyus), Hippopotamus (Hexaprotodon sinhaleyus) & Tiger (Panthera tigris) dated to 17,000-13,000 ybp belongs to the Pleistocene Epoch, could be identified during the recent excavations of the alluvial deposits in Sabaragamu basin. Isolated living Elephants, Sambar Deer & Eel (Anguilliformes ssp.) are unique to this area. The detailed study of the limestone cavern at Pannila mountain revealed that it is of 750 meters in length. The height of the cave entrance is 300 cm (3.5 feets) of which 60 cm filled with water, where special cave characteristics are visible. Stalagmite and stalactites of  5 m height formed after re-crystallization of pre-existing limestones could also be observed at the core of the cave. The studied limestone cave popularly known as ‘Pannila Hunugala’ is a part of the basement marble bed in the Highland Complex of Sri Lanka belongs to the Precambrian age. It is postulated that the same marble bed is extended to the marble beds located at the Samanalawewa, Waulpane and Rakwana. The action of chemical weathering occurred in the recent times makes it secondary features like stalagmite and stalactite. It is interesting to study that the existence of animal fossils within and around the cave is an indication of the period of cave formation, which probably contemporaneously to the Pleistocene Epoch. It was reported in the literature that during the Pleistocene Epoch, the entire island  experienced heavy rain fall resultant the growing of thick rain forests, of  which Sinharaja is one of the best existing example (Deraniyagala 1958). These heavy showers created large lakes and marshes in the Sabaragamuwa basin providing habitats for a number of marsh-loving mammals and other animal species mentioned above that were once lived in Sri Lanka and have got extinct as a result of the Earth’s Precession change in the following period.

Fig 01 : Distribution of limestone (+ marble) formation in Sri lanka

A.Pannila Hunugala(Sinharaja heritage site)  , C. Cavity of  right bank at river level in Samanalawewa. , D . Handagiriya( Balangoda), B.Model  for action of chemical  weathering formations of  limestone cave.

Key Words:Sinharaja Forest, Crystalline Limestone, Paleontology, Pleistocene Geology, Sri Lanka

E mail: ecoastronomysrilanka@gmail.com

Copyright©Palaeontology Network PGIAR –Palaeobiodiversity Batch 2015- 2016 

EXTICTION OF QUATERNARY MAMMALIAN HABITATS OF MEGAFAUNA IN SABARAGAMU BASIN - SRI LANKA

EXTICTION OF QUATERNARY MAMMALIAN HABITATS OF MEGAFAUNA IN SABARAGAMU BASIN - SRI LANKA

 ^1#Aravinda Ravibhanu Sumanarathna ²Jinadasa Katupotha ³Kamal Abeywardana

^1,3 South Asian Astrobiology & Palaeobiology Research Unit of Eco Astronomy Sri Lanka.

² Department of Geography: University of Jayawardenepura

¹Faculty of Enviroment & Natural Science University of Southampton –United Kingdom

Email: Ara22ravibhanu@gmail.com

ABSTRACT

The Quaternary includes two geologic epochs: the Pleistocene and the Holocene. Both epochs divided to faunal stages and human cultural phases based on climate and sea level cycles for the past three million years. Quaternary ice age begins roughly 2.58 Ma with cool and dry climate conditions. Australopithecines and many of the extinct genera of mammalian mega fauna appeared in this time. Thus, the Quaternary period show the extinctions of numerous predominantly larger, especially mammalian mega faunal species, many of them lived during the transition from the Pleistocene to the Holocene epoch. The debate on the demise of the mammalian megafauna is often characterized by two highly polarized points of view: (1) climate-induced extinction; and (2) human-induced extinction. In Pleistocene period most parts of the Northern Hemisphere were covered with glaciers creating a cold climate. Due to this glacial formation the main sea level was much lower than today. The low sea level facilitated the connection of Sri Lanka with the Indian mainland with a land bridge. Therefore a number of mega and micro fauna was able to cross to Sri Lanka from India. The last land bridge was emerged around 7500 yr BP. In Pleistocene era Sri Lanka experienced heavy rainfall and covered with rain forest. These heavy showers in the Sabaragamu basin provide habitats for a number of Marsh loving mammals and other animals. However at the end of Pleistocene the climate changes resulted in the extinction of  number of a animals. Pleistocene fauna in Sri Lanka is known as Rathnapura Fauna. These fossils were found in alluvial deposits of Sabaragamu basins.

Key Words:    Quaternary mammalian, Sabaragamu Basin, Ratnapura fauna, Extinction, Gem        gravels.

Paranomic view of Mount Sri Pada

During the Pleistocene, Sri Lanka experienced heavy rain fall and the entire island was covered with rain forests. These heavy showers created large lakes and marshes in Sabaragamuwa basin providing habitats for a number of marsh loving mammals and other animals.Image © Aravinda Ravibhanu 2013