On Changes of the Sea Level effected by Existing Physical Causes during Stated Periods of Time

Abstract

In this communication, the author first calculated the probable amount of the solid matter annually brought into the ocean by rivers and other agents, in suspension and solution, and the conclusion arrived at is, that the quantity of detritus thus distributed on the sea-bottom would displace enough water to cause an elevation of the mean ocean-level to the extent of at least three inches in 10,000 years. An attempt is then made to compute the number of such periods of 10,000 years that must have elapsed during the accumulation of the immense mass of freshwater deposits said to exist in the valley of the Mississippi. The calculation is made from the data collected by observers in America, as to the extent of the deposits in question: and it is 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 in 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 itself. From the data submitted, it would appear that the accumulation of the alluvial deposits of the Mississippi must have occupied a great number of periods, during each of which a mean elevation of the sea-level to the amount of at least three inches may have occurred; and that