180 



THEOKY. 



Washington. Mass., summit level of Western Rail- < 

 road, L, . . . ( 



Between Albany and Schenectady, N. Y., on Hudson 

 River, ...... 



On Western Railroad, east of Hudson River, A, 



MORAINE TERRACES. 



Norwich, A, 



Strafford, A, 

 Ripton, A, 



SEA BOTTOMS. 



1378 



1590 



1O 



Washington and Williamstown, A, ... 

 South Troy, A, 



Highest elevation of Champlain clays, . . 

 Fossil marine shells in Vermont, 

 Fossil marine shells at Montreal, .... 

 Clay beds in Memphremagog valley, . 



We have given above a Tabular veiw of all the terraces and beaches in the State, that we have measured, 

 or that we could find recorded by other authorities. The letter A annexed to the localities, indicates that 

 the heights were obtained by the Aneroid Barometer. L signifies, in the same position, that the heights 

 were obtained by Leveling. All those ascertained by leveling, were taken from the Illustrations of Surface 

 Geology. A few other beaches from other parts of New England have been added, for the sake of compar- 

 ison with those in Vermont. When there are two figures against each locality, and connected by a brace, 

 the upper one denotes the height of the Beach or Terrace above the stream to which it is contiguous ; and 

 the lower one denotes its height above the ocean. When there is only one figure present, it may be the 

 height above either of these levels, and the particular one in each instance is specified by some additional 

 explanation. The importance of tabulated heights of Terraces and Beaches cannot be over-estimated. 

 For by them we may learn what beaches, in different parts of the county, have the same height above the 

 ocean ; and may discover whether there is any such occurence of both terraces and beaches at successive 

 levels all over the State and country, as to sustain the theories of most geologists, who maintain that they 

 were formed by paroxysmal movements of the continent upwards, and it will form an excellent standard 

 by which to test the truth of all theories respecting their origin and distribution. 



CONCLUSIONS FEOM THE FACTS PKESENTED. 



It has been already stated that, lithologically, alluvium may be divided into two parts- 

 Drift, and Modified Drift; and chronologically into four periods, in each of which the 

 continent was differently situated in respect to the ocean, viz., the drift period, when the 

 continent was under water at its greatest depth ; the leach period, when it began to emerge ; 

 the terrace period, when the continent rose to nearly its present situation, and the historic 

 or present period. The oldest of these periods has already been dwelt upon fully. We 

 have seen that the continent began to sink in the newer pliocene period, until the approach 

 of the icebergs or some other cause exterminated the life of that period in Vermont, and 

 it continued to sink, till it had sunk to a depth of 5,000 feet. Next the movement was 

 upward, and after it had risen about 2,400 feet, beaches began to form on the highest 

 mountains. At this point we take up the history and endeavor to decipher the hiero- 



