182 THEOKY. 



2. The successive beaches and terraces, as we descend from the highest to the lowest, in 

 any valley, seem to have been produced by the continued repetition of essentially the 

 same agencies by which the materials originally coarse drift have been made finer 

 and finer, and have been more carefully sorted and arranged into more and more perfect 

 terraces and beaches. 



3. The largest part of the materials constituting the terraces, beaches, &c., is modified 

 drift, that is, the fragments of rocks, &c., torn from the ledges by drift agencies, washed, 

 rounded and worn down by water. 



This position is established by the first proposition, that all the phenomena of drift are 

 found lying beneath the various forms of modified drift. The striae occur in valleys as 

 well as on the hills, sometimes at the very water's edge. In some parts of the country 

 there may have been a greater amount of rock eroded since the drift period ; but nowhere 

 an amount that will compare with the quantity that had been removed previously. At 

 Bellows Falls, upon Connecticut River, the rocks at the top of the falls, even to the 

 water's edge, exhibit strise and other marks of drift, although the cataract has undoubtedly 

 receded considerably at this spot since that force acted. At Brattlcboro the slate on the 

 west side of the river shows drift furrows only a few feet above the river. Plere too was 

 once a gorge ; but it was worn out earlier than the drift period. At Fairfax, upon the 

 La Moille River, striae may be seen within five feet of the surface of the water ; while in 

 Wolcott evidences of water action, such as pot-holes, may be found fifty feet above the 

 river before striae are discovered. And in Wallingford, upon Otter Creek, may be seen a 

 great pot-hole 50 feet above the creek. Similar examples may be seen upon every river 

 in the State. 



4. Hence, wherever, upon all these rivers, we can find marks of drift agency low down 

 on the rocks at gorges, we cannot suppose that rocky barriers closed those gorges during 

 the period when the terraces were forming ; and, therefore, we cannot call in their aid to 

 explain the formation of the terraces and beaches. 



5. Former beaches of the ocean may be found at all heights from the present level of 

 the ocean to the height of 2500 feet above it, in New England. In Vermont they are 

 found between the heights of 100 and 2200 feet. 



In the table of heights of beaches, etc., we have given the elevations of all the higher 

 beaches in New England that we could find recorded, that it might be ascertained whether 

 any considerable number of them might have been formed at the same time. The follow- 

 ing cases are those that approximate most nearly to one another : In Thetford, 878 feet, and 

 near the State line between Mass, and N. Y. on the western railroad, 890 feet. In North 

 Ashfield, Mass., 1031 feet; Conway, Mass., 1033 feet, and in Newport, Vt., 1060 feet; East of 

 Hudson River, near Albany, 1111 feet; Pelham, Mass., 1151 feet, and Shutesbury, Mass., 

 1167 feet. In North Ashfield, Mass., 1216 feet; Shutesbury, Mass., 1217 feet, 'in East 

 Corinth, Vt., 1239 feet; Elmore and North Hardwick, Vt., on both sides of La Moille 

 River, 1240 feet ; Brownington, Vt., 1274 feet, and in North Norwich, Vt.', 1287 feet. In 

 North Ashfield, Mass., 1321 feet ; North Norwich, Vt., 1337 feet, and on Copperas Hill, 

 Stratford, Vt., 1340 feet. In Heath, Mass., 1561 feet; White Mt. Notch, N. II., 1569 feet, 

 and on the summit level of the Western Railroad in Washington, Mass., on the continua- 

 tion of the Green Mountains, southerly 1590 feet; On the summits of the Green Moun- 



