526 Geological Society. 



mains at only one point in the line of the railway, Mr. Strickland 



states that he can offer no other explanation than that previously 

 proposed by him *, namely, that after the beds of marine gravel had 

 been deposited and laid dr)' by the elevation of the land, a large 

 river or chain of lakes extended down the valley of the Avon, at a 

 height varying from twenty to fifty feet above its present course ; 

 and that the gravel previously accumulated by marine currents was 

 reraodified by the river, and mixed up with remains of mammalia 

 which tenanted its banks, or of moUusca which inhabited its waters. 



Local gravel. — Tliis species of detritus occurs abundantly at Chel- 

 tenham, and consists exclusively of detritus from the oolites and lias 

 of the vicinity. No bones or terrestrial remains have been found in 

 it ; and, therefore, the author assigns to it, in the absence of other 

 evidence, a marine origin. 



Modern alluvia. — The only deposits of this nature mentioned in 

 the paper, are the peaty accumulations on the banks of the Avon 

 and its tributaries. 



The memoir was accompanied by a copy of the Railway Section, 

 and of the Tewkesbury branch, and the junction branch from the 

 main line to the London and Birmingham Railway, presented by 

 Capt. Moorsom, but coloured geologically by Mr. Strickland. 



A letter addressed to Mr. Murchison by Capt. Lloyd, dated 

 London, May 11th, 1840. 



Having read in the instructions prepared by the Royal Society for 

 the Antarctic Expedition under Capt. James Ross, that the island of 

 Bourbon presents indications of the sea having formerly occupied a 

 higher level than at present, and having observed similar appear- 

 ances in the Mauritius, Capt. Lloyd was induced to lay the follow- 

 ing facts before the Society. 



The island of Mauritius is belted by an enormous coral reef 

 throughout its whole circumference, except for about ten miles of 

 the broadest and extreme southern side, or from Point Souffleur to 

 Sou iliac, commonly called Port Savanne. Along that part of the 

 island the coast is bold, and consists of a basaltic rock. 



Near the Rivifere des Galets, between Savanne and the Bale du 

 Cap, the sea foams against a barrier of coral from five to fifteen feet 

 in height, and wears it into the most fantastic shapes. At a con- 

 siderable distance inland, and almost concealed by trees and shrubs, 

 are two remarkable points or headlands of coral, from twenty to 

 twenty-five feet above the present level of the sea. They present 

 the same marks of abrasion as the barrier reef now undergoing 

 the action of the waves. The Observatory, Port Louis, is built also 

 on a stratum, ten feet above high-water mark, of very hard coral, 

 which requires blasting. There are besides in several parts of the 

 island, and at considerable distances inland, enormous blocks of 

 coral surrounded with the debris of oyster and other shells and broken 

 corals. Appended to Capt. Lloyd's communication are two letters 

 from agents employed by him to collect information respecting in- 

 land blocks of coral. One of the letters is from Mr. Hill, sun'eyor 



* Reports of British Association, vol. vi. Sections, p. 64. 



