TRANSACTIONS OF THE SECTIONS. 87 
ἡ. The commencement of this action may run back to the time when the rock 
was consolidated, and was first elevated above the ocean. 
8. The regions where these erosions have taken place, may have been once or 
more beneath the ocean after the work commenced; and the action of the ocean 
during these vertical movements may have modified the gorges. 
9. The period requisite to produce the erosions that have been pointed out, must 
have been inconceivably long, corresponding to the other facts of geology, but more 
easily understood by men generally than other evidence derived from organic re- 
mains. 
On Terraces and Ancient Sea Beaches, especially those on the Connecticut 
River, and its Tributaries in New England. By the Rev. Epwarp 
Hircucock, D.D., LL.D., Pres. Amherst Col., and Prof: Geol. 
The classes of terraces and beaches that are formed of loose materials on the 
globe are three:—1. River terraces. 2. Ancient beaches around ponds and lakes. 
3. Ancient sea beaches. 
Those described in this paper are all more recent than the drift, though tertiary 
strata sometimes have a terrace form. 
The materials of the post-diluvian terraces are derived—lIst, from drift, modified 
by subsequent aqueous or glacial agency; 2nd, from the erosion of the solid rocks 
by water and ice. 
The sides of the valleys of the rivers of New England, and eminently those of Con- 
necticut River, are composed at the surface as follows, beginning at the top of the 
hills :—1. Unmodified drift, sometimes pierced by rock in places. 2. The same ma- 
terials more rounded, yet coarse, and disposed somewhat on a level, especially in the 
directions of the valley, resembling a modern sea beach. 8. The materials not only 
rounded, but more or less sorted into layers of gravel and sand, forming fringes on 
the sides of the valley, and sometimes showing irregular mounds on the top, analogous 
to moraines. 4. Terraces of rounded and sorted materials, gravel, sand and loam, 
with level tops. 5. Alluvial meadows, sometimes overflowed. 
Means of distinguishing between Drift and Modified Drift.—1. Unmodified drift 
contains the greatest amount of angular blocks. 2, It is also usually unstratified, 
though limited spots in it sometimes show lamination; whereas modified drift is usually 
more or less sorted and stratified. 3. The former conforming to the surface, unless 
too steep, the latter more or less Jevel-topped. 
Character and Position of the Materials.—Usually the highest beach or terrace 
consists of coarse materials, such as gravel, often very coarse; the next lowest, of 
coarse and fine sand; the next, of clay; and the lowest, of loam, or a mixture of 
sand and clay. 
Means of distinguishing between Sea Beaches and Terraces.—1. The lowest shelves 
are usually the most perfect, having an appearance highly artificial, and forming, in 
fact, the sites of some of our most beautiful villages. 2. As we ascend, the tops of 
the shelves become more and more broken and irregular. 3. At length we reach re- 
arranged and modified materials, that are not level-topped, except lengthwise of the 
valley, and are more or less rounded towards the valley: these resemble beaches. 
4. But whenever these materials lie along the banks of a river, or the former bed of 
a river, so that they might have been deposited by that river at a higher level, when 
its barriers might have been blocked up, they constitute terraces. But when they 
exist where water, standing at that height, must have communicated with the ocean, 
they are beaches. 
‘arieties of River Terraces.—1. The lateral terrace, occurring only along the sides 
of rivers where there are meadows. 2. The delta terrace, existing at the mouths of 
tributaries : generally the delta terraces are fringed by lateral terraces. 3. The gorge 
terrace, found sometimes at both ends of a gorge, cut out by ariver. 4. Glacis ter- 
race, oceurring in the form of a glacis in alluvial meadows. - 
Here the author introduced many details of the terraces in the valley of Connecti- 
cut River and its tributaries, where they occur in several basins, which might have 
been more or less separated since the drift period by gravel or ice ; as these wore away, 
the terraces were produced. Drawings of 154 of these terraces and beaches were 
