Paleoclimatic Change from the Middle Quaternary to Holocene Periods in the Kalu Ganga River Basin, Sri Lanka

Abstract

AttachedSri L anka is a tropical country, w hich is im portant to study the w eathering erosion, transportation and deposition processescaused by riversand surface running w ater. A ccording to th e geological tim e scale, these processes w ere evident during th e Q uaternary period. T herefore lots o f sedim entary deposits are found w ithin th e costal low land and upland regions, and gem bearing m inerals are found w ithin the highland com plex. These m inerals have been deposited island-w ide by the process o f river erosion and transportation. Especially the K alu G anga river basin is prom inent for the sedim entation o f gem bearing m inerals.A ccording to the paleontological evidence in Sri Lanka, there is a stratigraphy o f gem -bearing sedim ents in the K alu G anga river basin in term s o f th e depth o f sedim ents and num ber o f gem -bearing layers. O ur research focuses onthe study o f this particular stratification pattern in K alu G anga river basin. F or th is purpose, an investigation w as carried ou t in ten gem m ines representing the m iddle catchm ent o f the river basin. M ethodology includes G IS m apping, G PS location, sieve analysis, organic content analysis and pipette analysis. T here is spatial variation in th e num ber and the depth o f gem bearing and non-gem bearing sedim ent layers in the K alu G anga river basin. It is very im portant to find out th at tw o gem bearing sedim ent layers belonging to the different geological periods can be found in the m iddle catchm ent area.Since the lake sedim ents w ere found below the low est gem bearing sedim ent layer in the catchm ent, it is assum ed that there w as paleontalogical m orphology o f a lake in the m iddle o f Q uaternary period