Jrom the melting of the Quaternary Glacier. » 196 
the square of the velocity (supposing them of like density) a 
stream of 2-miles an hour at bottom would carry along stones of 
about 0°6 inch in diameter; and one of 4 miles, stones 24 
inches in diameter. The mean velocity is generally about a 
third to a sixth greater than the bottom rate, the differences 
diminishing as the velocity increases. the mean velocity 
were 10 miles an hour, that of the bottom would be over 8 
miles (unless greatly impeded by transported material)—rapid 
enough to scour down to stones and soli 
This argument is not based on the depositions made by the 
stream; for these were more or less made over the flood- 
grounds of the river as the waters rose; and the waters over 
flood-grounds, even in the case of rapid streams, are variously 
impeded by the amount of transported material, friction in the 
shallow waters, and obstructions, often dam-like, due to the 
uneven surface beneath; but on the transporting force of the 
stream at the time of maximum flood, when all the terrace- 
waters. It may be questioned whether the,lower terrace of 60 
to 80 feet above present low water, which is almost everywhere 
—if the mouth of no tributary is near—made of sand or 
loam where not of clay, was actually the bottom of the flooded 
stream ; whether, the waters did not excayate down to stones 
and rock, so that this terrace is of subsequént formation. 
this supposition does not rid the subject of the fact that the 
flooded stream did not take up and carry off the sands of its 
bottom, For the range of higher terraces usually 140 to 160 
feet above low water in the river, were at the time under 50 
feet in depth of water; and these, away from tributaries, usually 
consist at top and below of fine sand or loam, or of fine gravel. 
The great terrace-plain north of White River Junction was one 
of this kind with 50 feet of water above it; and it consists at 
chiefly of sand with some clay. The materials of the corre- 
sponding terrace near Windsor are still finer. The high ter- 
race-plain east of Greenfield and south of Turner’s Falls, be- 
tween Montague City and Miller’s Falls, called the Montague 
City plain, lies directly in the way of the Connecticut, as stated 
on page 191; and although flowed over at the highest flood by 
water 10 to 30 feet in depth, it consists chiefly of fine sand, or 
loamy sand, with some clay, except on its eastern and north- 
eastern side, where it received contributions from the violently 
torrential Miller’s River. 
_ Thus all parts of the valley bear like testimony to a velocity 
'n the waters at maximum flood which was not great enough to 
carry off fine gravel, and this means a velocity not exceeding 
