258 Mr. A. Tylor on Changes of the Sea-level effected by 



In naming the new bodies described in the present paper, I 

 have, in conformity with the nomenclature of the organic bases, 

 adopted the principle of employing the termination " ium ** 

 when the body unites with one equivalent of oxygen, chlorine, 

 sulphur, &c., like ammonium, and the terminal " ine *' when, 

 like ammonia, it combines with two additional atoms. 



XLI. On Changes of the Sea-Level effected by existing Physical 

 Causes during stated Periods of Time, By Alfred Tylor, 

 F,G.S.^ 



Introduction. 



THE First Part of the ensuing paper is occupied with the 

 details of the probable amount of the solid matter annu- 

 ally brought into the ocean by rivers and other agents, in sus- 

 pension and solution ; and the conclusion is arrived at, that the 

 quantity of detritus thus distributed on the sea-bottom would 

 displace enough water to cause an elevation of the ocean-level to 

 the extent of at least 3 inches in 10,000 years. 



In the Second Part an endeavour is made to compute the 

 number of such periods of 10,000 years that must have elapsed 

 during the accumulation of the immense mass of recent fresh- 

 water strata said to exist in the valley of the Mississippi. 



The calculation as to the latter is made from the data collected 

 by observers in America, of the extent of the deposit in question ; 

 and it is here supposed, first, that in former periods the same 

 quantity of mud as at present has been annually carried into 

 the Gulf of Mexico ; and secondly, that the amount of sediment 

 deposited on the delta and plains of the Mississippi does not 

 exceed one-tenth part of the solid material which has been carried 

 out (suspended in the water of the river) into distant parts of 

 the Gulf of Mexico, or into the Atlantic Ocean itself. 



From recent accounts by Mr. C. EUet, of the United States, 

 it appears that a column of fresh water, \\ mile wide and about 

 7 feet deep, is constantly entering the Gulf of Mexico at a speed 

 of 2 to 2 J miles per hour, and floats on the surface of a stratum 

 of salt water, to which it partially communicates its own velocity. 

 And below this a stratum of sea-water is found to be flowing in 

 an opposite direction to that of the two strata of fresh and salt 

 water above it. See figs. 1 and 2. 



From the data submitted, it would appear that the accumula- 

 tion of the alluvial deposit of the Mississippi must have occupied 

 a great number of periods, during each of which an elevation of 

 the sea-level of 3 inches may have occurred. 



* Communicated by the Author. 



