ON THE GEOLOGY OF THE ISLAND OF AQUIDNECK. 525 
beach of Newport. South of this point we have two considerable 
ponds, Almy’s and Lilly pond ; both of these and the marshy pond 
just to the west of the latter are glacial excavations. The last is 
closing by the accumulation of vegetable matter, its waters having 
become shallow enough to bear an abundant vegetation, which is 
rapidly converting it into a peat bog. The island is singularly 
free from perfectly level lowlands, such as are formed by the filling 
up of old ponds, and the few sheets of water which remain are not 
disappearing with the rapidity usual in New England. 
The process of occlusion in these ponds can be studied to ad- 
vantage in the marshes between the Lilly pond and Bateman’s. 
= The vegetation, consisting of a variety of marsh plants, begins 
its growth at the shore where there is a sand beach and bold 
water, but it may be a long time before its foothold can be made 
' l. Some accident such as a landslide or a fallen tree makes 
4 little shelter, so that the plants get a hold in the water. Ina 
short time they make a bed a foot or more in thickness; their 
roots go so deep that soon they can stand a considerable beat 
= Ofthe wave. The commotions in the water tear away and dis- 
tribute over the floor of the pond a part of the mass, but it con- 
tinues to grow and gains on the clear space, often at the rate of 
several inches a year. Where the circumstances are favorable, 
we find the mat of plants extending from the shore over the pond, 
without, touching its floor, sometimes for only a few feet, again, 
at times, covering many acres with its growth. The accumulation 
of sediment under these. conditions takes place in a singular 
fashion ; the mat of vegetation floats upon the surface of the pond, 
and sinks deeper and deeper as it grows until, finally, it rests upon 
the bottom. It then continues to grow until it has gotten itself 
80 far above the water, that the vegetation no longer has the neces- 
Sary amount of water.* ; 
The topography of the island, as a whole, is remarkable for the 
small extent to which it expresses the structure of the rock below. 
NN T E oP Se a oe a et es 
a BE easy 
= ep rat ie ees 
a] 
CR a pet e a A A TAS Pe es Og E A GAE 
l 
i 
jtnries 
_*This proce a : a ag = : : 
et implements of man: where a stone tool remained on the surface itwas likely to 
cos od again, and used until its very chips were worn away- Falling into 
tes mg through some crevice in its top érust, it sank to a secure hiding place. 
easta ents can penetrate so deeply into bogs makes them very untrust- 
"i ad ape eg . An implement of the stone age may get buried in the solid 
hed feet from the surface, while a modern piece of work falling into a more 
oe may sink far below it. When the bog comes to be excavated the deeper 
bject is naturally, but mistakenly, taken for the older. l 
