210 
IOWA ACADEMY OF SCIENCES 
DUNE MOVEMENT. 
The rapidity with which dunes move inland varies from a few inches 
to a number of feet annually, depending upon the force of the wind and 
the location of the dunes with reference to interior obstruction. Studies 
have not been prosecuted to a sufficient extent in this country for us to 
make any definite statements as to rapidity with which dunes along our 
sea-coast or inland are moving, but observations made during an average 
season lead us to believe that depending upon the severity of the winds 
our dunes have about the same rate of movement as those in France and 
other countries. Bordering the Bay of Biscay in Gascony, France, there 
is a belt of sand dunes w'hich vary in width from one-quarter to five 
miles, and cover an area of about 250,000square miles. Where these 
dunes are not fixed by grass and a group of trees they advance eastward 
at a mean rate of about sixteen feet per year. Marsh says: 
“It is not known historically when the dunes began to drift, but if 
we suppose their motion to have always been the same as at present 
they would have passed over the space between the sea-coast and their 
present eastern border and covered the area of 250,000 square miles in 
fourteen hundred years.” 
EXTENT AND WOKK OF MOVING DUNES. 
From written records it is known that these dunes have buried exten- 
sive forests, fields and villages; changed the course of rivers, and the 
lighter portions of the sand carried from these dunes by the winds, even 
while net in sufficient quantities to form sand hills have turned lands 
formerly fertile into sterile stretches. Along the coast of Jutland in 
Denmark, the dunes, in the course of two or three centuries, have moved 
several miles inland covering forests and villages. In our country the 
drifting dunes have done immense damage upon Cape Cod, in the south- 
ern half of Long Island, on the coast of New Jersey and along the Pacific 
coast from the mouth of the Columbia river southward to Golden Gate 
Park in California. Small but active areas of dunes along the eastern 
shore of Lake Michigan and along the valley of the Columbia river in 
Washington and Oregon have also caused much damage by covering rail- 
road tracks and encroaching upon fields and cities. Along the Snake 
river division of the Oregon Railway & Navigation Company’s line, as 
much as from $5,000 to $8,000 per year has been spent in keeping the 
tracks free from sand. At Riparia on the above division large railroad 
shops and other buildings were moved away to prevent their covering 
by rapidly moving dunes. The Pere Marquette Railroad which skirts 
the southeastern shore of Lake Michigan, has spent considerable money 
in keeping their tracks free from encroaching sand. There have been 
several railroad wrecks in the country, of more or less importance, as a 
result of sand being blown over tracks during severe storms. A wreck 
near The Dalles, Oregon some six years ago caused considerable loss of 
life and property. Injury to forts along the Atlantic coast from moving 
aimes has caused the War Department to call upon the Scientific Bur- 
eaus of the government to aid them in keeping back these dunes from 
the immediate location of the forts. 
