160 CEYLON PEARL OYSTER REPORT. 



further exposure of coral rock, which has been described as a fossil atoll, lies in the 

 interior immediately to the North of the Temple of Rameswaram. A large part of 

 the island is covered by sand dunes which extend as a long spit as far as Thanni- 

 Kodi on the south-east. These dunes hide the solid rocks of which the island is 

 built, but a series of trial borings made across the island from north to south, two 

 miles east of Pamban Town, did not show any southward extension of the coral reef, 

 but a coarse calcareous sandstone very modern looking and imperfectly consolidated. 

 It is unfortunate that a piece of this rock was not available for comparison with the 

 calcretes found on the paars, but from the detailed descriptions of Foote and Walther, 

 it corresponds exactly with those found in the Periya and Cheval paar areas. 



The chain of small islands east of Thanni-Kodi, and Manaar Island itself, also 

 consist of similar calcareous sandstones. They are continued to the west across 

 Pamban Strait and are seen bordering the coasts of Tonitoray Spit. On the east, 

 according to Richthoven, the low lying plain forming the northern extremity of 

 Ceylon has a coralline formation for its substratum. Similar rocks can be seen at 

 intervals all along the East Coast of India, and have been described under the name 

 of Cuddalore Sandstone. Again, along the West Coast of India, occurs the " littoral 

 concrete," described by Oldham* as " an agglutinated calcareous shelly grit raised a 

 little above sea level in several places." " It consists of shells, corals, pebbles, and 

 sand cemented more or less thoroughly by carbonate of lime.'' " The beds may have 

 originally been sand spits or beach deposits." All these deposits contain none but 

 recent shells, exactly like those now living in the neighbouring seas. 



SuESst attributes the emergence of Adam's Bridge and the " littoral concrete" to a 

 negative eustatic movement of the sea level in post-Tertiary times, and brings 

 together a mass of evidence to show that the negative movement was widespread, 

 embracing a large portion of the northern hemisphere. He surmises that the 

 emergence may have been so recent that the great Hindu epic, the Ramayana, which 

 treats of the building of Adam's Bridge, may be a poetical rendering of events 

 witnessed by man. Although we have no certain evidence that the Bridge was at 

 any time continuous, we have historic data to prove that the Island of Rameswaram 

 was once united with Tonitoray Spit. If, as 1 suggest, the various links in the chain 

 of islands represent emerged " paars," we have no reason to suppose, judging from the 

 distribution of those now forming, that they were ever united. 



In any case, the barrier, whether continuous or broken, would profoundly influence 

 the deposits laid down in Palk Bay. Cut off from the currents sweeping up the 

 coasts from the south, the conditions would be favourable to the deposition of mud, 

 such as we find covering the floor of the bay, and sand would be confined to the 

 shores. It will be noticed, however (p. 149), that casts of shells occur in the mud, 

 and these are composed of sand. The shells have been completely removed, and the 



* ' Manual of the Geology of India,' 1893. 

 t ' Das Antlitz der Erde,' vol. 2, p. 647. 



