16 ROYAL SOCIETY OF CANADA 
land where it holds its own for a time, but ultimately fills up and 
re-establishes itself at the original starting point. This “ marching of 
the inlets” is due to the gradual drift of sand along the coast in 
obedience to the set of the shore currents; but as this influence relates 
chiefly to the Atlantic coast of the southern states, such “ marching 
of the inlets” is a factor which does not enter into the present dis- 
cussion.! As a matter of fact, the inlet connected with the marsh 
which forms the special subject of this paper, cannot shift its position 
because of its location between two headlands which are but slightly 
distant from one another. | 
In exceptional cases the sea water may also find its way into the 
marsh through a back channel, and in some instances such communi- 
cation from the rear may be the only means by which the marsh becomes 
flooded by salt water. As this is a feature of the marshes with which 
our present studies are particularly connected, it will be discussed more 
fully in that connection, but it may be useful to indicate that such 
flooding is developed as a secondary feature in the growth of the marsh, 
resulting from the operation of important physical changes in the crust 
of the earth. 
With respect to the water courses, there is usually a main channel 
into which several lateral channels drain, and these latter tend to 
become more numerous toward the lower end of the marsh. Some- 
times a lagoon is left behind the sea wall, as at Hampton, and it then 
forms a small but somewhat useful harbour of refuge; but not infre- 
quently the main stream discharges directly through the sea wall 
without material enlargement, as at Brave-Boat Harbor, York, Maine, 
or into a larger stream as at Newburyport. These features are to be 
regarded as expressions of the varying extent to which the original 
lagoon has become filled by silting and the growth of vegetation, as well 
as to the erosive action of the flowing tides. Through the system of 
channels the tide ebbs and flows. At the time of spring tides the 
inflowing water spreads over the banks and floods the entire area; but 
at neap tides the surface of the marshland is slightly above water, or 
as Shaler has expressed it (6) “ Their range of height is such that all 
ordinary tides bring salt water about the roots of the plants, while the 
high tides suffuse them altogether. Their conditions of development 
are so equated with tidal phenomena that they may be alternately bared 
and suffused by the salt water.’ The conditions thus described are 
precisely those which would offer very favourable environment to the 

* Since the above was written, I have been informed that such a marching 
inlet is to be found on Prince Edward Island, where there is a small extent 
of coastal plain. 
