[PENHALLOW] DEVELOPMENT OF CERTAIN MARSH LANDS 15 
fertility as well as their natural adaptation to successful irrigation by 
means of the inflowing streams of fresh water, they would, when 
reclaimed, be of great value for agricultural purposes. How far such 
an expensive undertaking as the construction of necessary dams would 
be justified by estimated returns, is a matter of calculation, but the 
experience gained in reclaiming the extensive marshlands at Marshfield, 
Massachusetts; and the maintenance of an extensive system of dykes 
in Annapalis valley, Nova Scotia, since the time of the early French 
settlements, whereby previcusly flooded areas have been converted into 
the most profitable grass lands, would seem to imply that the under- 
taking would be a remunerative one. 
A third feature of marshlands is, that whether there is a rear con- 
nection with the ocean or not, the outward face is protected and cut 
off from the sea by a sea wall of varying height and thickness. This 
wall is always composed of beach pebbles, and it may be one hundred 
feet or more in thickness at the base. At the foot of the wall on its 
outer face, which is usually quite steep—the stones lying at the 
angle of repose—there is a gently sloping beach of sand which 
may extend seaward for a long distance. Usually this sandy beach lies 
much below the level of the marsh on the opposite side of the barrier 
ridge, but an exception to this appears at Sea Point, Kittery, Maine, 
where the sea wall is but a few feet above high water mark, and the 
sand of the lower beach is brought up to the level of the marsh within. 
At low tide the waters from the more elevated marsh area behind, seep 
through the porous wall and descend in small rivulets over the exposed 
sands where they produce in miniature, all those features of water 
erosion so well exemplified in the great cañons of the western United 
States, and in all of our rivers. 
At every high tide, especially of every spring tide, and more 
particularly when driven on the coast by a storm, the water rises to the 
level or even above the level of the marsh lands which are thereby 
flooded if there is an opening in the barrier, but if the latter be closed, 
as in the case mentioned, the occurrence of exceptionally high water 
does not involve any appreciable seepage into the marsh where the water 
level appears to depend upon other factors. 
In all such marsh lands, the access of the sea water appears to be 
determined by breaches in the sea wall or barrier beach, and Shaler (1) 
has shown that the formation of such breaches by erosion through an 
overflow of the interior lagoon, conforms in many cases, to well defined 
external influences. Thus the breach in the barrier commences at its 
junction with the headland. Year by year it moves forward, filling 
behind and cutting in front until it eventually gains the opposite head- 
