DETAILS. 103 



higher level, which have terraces also; and usually above them we find beaches, still 

 retaining the same relative position to the terraces. 



VI. SEA BOTTOMS. 



The bottom of the present ocean, along the coast, is in many places covered by deposits 

 of sand and gravel, left there seemingly by tidal action, and presenting often numerous 

 ridges and depressions. Often, too, bars are formed across the mouth of harbors, produc- 

 ing lagoons. Hooks, also, are produced, where the currents sweep around headlands. 

 While these deposits are beneath the waters, they go by the name of shoals. If these 

 shoals, bays and harbors be raised out of the ocean, although they will be exposed to the 

 modifying influence of rivers and rains, their essential characteristics will be long 

 preserved. They are abundant in Vermont, in the great valleys that cross the State from 

 north to south ; being found at heights varying from 150 to 1500 feet above the ocean ; 

 and the lower beds contain marine fossils, of such animals as now live at great depths in 

 salt water. 



DETAIL OF THE FACTS. 



Nearly all the information, respecting the terraces and beaches, has been obtained 

 during the progress of the survey, and that without interfering with the study of 

 the older rocks. It has been a pastime, rather than a laborious undertaking. 

 Unfortunately our time did not permit us to take such careful measurements of their 

 heights as we could have desired. There was no room, amidst the great number of instru- 

 ments and amount of luggage and specimens to be transported in our carriage, for carry- 

 ing leveling instruments, and the Aneroid was not so accurate as we desired. Yet a few 

 sections of terraces were measured with this instrument for want of something better ; 

 and the facts thus ascertained, with others detailed in the Illustrations of Surface Geology, 

 have enabled us to give satisfactory generalizations upon the height and origin of terraces. 

 We can thus present the principal facts of the science of terraces, leaving the additional 

 observations and admeasurements to future observers. 



We will give the details in succession upon the terraces and basins of the five largest 

 rivers in the State, in order, commencing with the Connecticut and its tributaries, which 

 water more than two-fifths of the State; and then taking Otter Creek, Winooski River, 

 Lamoille River, and the Missisco River, which together water more than the other two- 

 fifths of the state. The remaining fifth will be properly noticed also. In all these streams 

 the terraces occur in basins, sometimes quite numerous, which we will attempt to describe 

 in order, beginning at the mouths of the rivers and proceeding to their sources. 



These basins may be connected by their highest terraces, or be separated by ridges, 

 through which gorges have been cut and deepened by the river alone, or with the aid of 

 the ocean. Formerly the spaces occupied by these basins must have been occupied by 

 narrow lakes or ponds. After finishing the River Terraces we shall next discuss all the 

 facts respecting Lake Terraces, Maritime Terraces, Moraine Terraces, Ancient Sea Beaches 

 and Ancient Sea Bottoms. 



