42 ROYAL SOCIETY OF CANADA 
spongy mass, it gradually found its way to a lower level until brought 
to the position in which it was found af the bottom of the cassandra 
zone. The structure of the peat layers, however, would seem to be 
opposed to this possibility, and there is then left only the alternative 
theory that the pipe was dropped by some cranberry picker at a time 
when the cassandra zone was still in process of growth. Acceptance of 
this theory would necessitate adopting the view that the whole structure 
of the marsh has formed within the last two hundred and fifty years or 
less. 
With reference to the time period of two hundred years as already 
stated, it should be kept in mind that the growth of the various bog 
strata proceeds quite independently of the elevation or depression of the 
general region, and it is, therefore, impossible to correlate the two 
phenomena. But in the growth of the marsh turf, there is a factor of 
great importance from which it may be possible to determine a time 
period, and this factor it is possible to ascertain with a reasonable 
amount of accuracy. 
The Piscataqua river above Dover Point, expands into a great, 
shallow basin known as Great Bay. At low tide navigation is confined 
to narrow and tortuous channels which lead to Durham and Exeter, the 
general area being made up of extensive flats covered with a heavy 
growth of marsh grass, the turf of which is quite thick. In winter 
the entire bay is frozen over, and it then constitutes a well known 
locality for the taking of smelts which are caught through the ice and 
shipped away in very large quantities. 
In early spring, usually in the month of March, the ice commences 
to break up, and every tide carries large quantities out to sea. It often 
happens that these blocks of ice, having been préviously frozen to the 
surface of the marsh, lift large blocks of the turf and either carry them 
out to sea or deposit them on the shore of the river where they then 
continue their growth and often cause much annoyance by their obstruc- 
tion of waterways or of olherwise desirable beaches. 
Sometime subsequently to 1868, probably in the spring of 1869, 
such a block of turf several square yards in extent, was landed on a beach 
a short distance above the long bridge. It continued to grow in thick- 
ness and area, spreading over the adjacent sand. In 1904 it was decided 
to remove this growth because of its interference with the utility of the — 
oeach. In cutting it out, it was found that the original surface of the 
turf was clearly defined by a line of cleavage with the newer growth 
which had spread laterally until the whole area occupied was quite twice 
that of the original mass. It was thus possible to define the limits of 
the newer growth with considerable exactness, and it was found to be 
