The Julesburg grit-advocate., 1910-06-02

IEeneS6 OF tnle eSef-act1V0
geological agency. Yet
even In some well-watered regions
dunes are familiar phenomena. Dunes
are simply drifts" Of sand. closely re-
sembling the snowdrifts OF winter and
protection against them IL secured by
similar means. As in snowy regions
Vhe sees long lines Of close board
fences some distance from the wind
ward side Of the railroad to stop the
drifting snow on its onward career, 20
he may in many places see wind
breaks to stop the drifting sand. But
in many cases where the windbreak
ID not suficient . constant force Of
workmen 10 necessary to remove the
sand from the track At stated inter.
walls or after every unusually severe
storm. At such places the railroad
companies. to their sorrow. learn the
enormous power of this constantly
acting geological force in transferring
finely comminuted earthly material
from one place to another.
One Of the best known localities for
observing dunes 10 found on the south
eastern shore Of Lake Michigan.
Nearly all. II not all. the railroads ap-
preaching Chicago from the east pass
through this series Of dunes ~ they
come around the southern end of the
lake. Many of the dunes are very
fresh. with NO covering Of vegetation.
and rise, like snowdrifts, 80 feet or
moro above the general level. Others
are Of such age that they have been
covered more or less with vegetation,
trees Of considerable size being found
upon them. But in all cases the &C.
ton of the wind. in moving the sand
southwark from the lake. 10 evident.
The wind blowing from the north
keeps an exposure of bare sand upon
that side and drifts 1t over into expo.
sures Of equally bars sand upon the
outer margin, The Width Of this belt OF
dunes afohhd the south end of Lake
Michigan averages a little more than
d mile. The material, being clean,
washed sand. Is unit Tor agricultural
purposes and the area is occupied by
very few houses, and those mostly be-
longing to railway employees.
The source of the material Of
which these dunes are composed and
the rate of its movement are subjects
Of great interest. The sand is de.
rived, In the first place, from the
shores of the lake farther north.
which are constantly being eaten
into by the waves and currents. All
along the western shore. from Evans
ton to Racine, the waves are wearing
away the shore at an average rate of
three or four feet per annum. The
material that falls into the lake from
the bluffs thus eroded is worked over
by the waves until the very finest
particles are washed out and floated
into deep water, while the sand re-
mains near the shore and is gradually
washed southwark by the prevailing
currents. Everyone in Chicago knows
how land il forming on the shore,
giving rise to legal contests as to own
ership. From observations Of the
United States engineers 1t was found
that 129, 900 cubic yards Of sand were
annually stopped by the two piers
which were extended out into the lake
to deep water. This vast amount rep
resented, however. but a fraction Of
the whole amount of sand that was
being carried by the currents past
Chicago to the south end of the lake.
reaching the south end of the
lake the sand is washed up by the
waves during storms and left for a
considerable portion Of the year ex-
posed to the action Of the winds,
which have drifted it out into the belt
of dunes, with which SO large por-
ton of the travelling public is famil-
lar. But, owing to the fact that the
prevailing winds of this region are
westerly, the largest accumulation Of
dunes is found upon the east shore,
in Michigan. Travellers upon the
Michigan Central railroad cannot fail
to have noticed these great drifts Of
sand, nearly 100 feet high. at Michi-
gan City. This belt of dunes, about
q quarter of mile wide, rising some
times to more than 100 feet in height,
extends northward all along the shore.
being specially prominent at st. 10
seph and Grand Haven. In many
places they threaten to overwhelm
whole villages and to compel the rail-
roads to remove their tracks to get
out of the way of the drifting mate
rial, while in some cases houses and
forests have been completely buried
out of sight.
1t has been profitable to dwell thus
fully upon the dunes around the
southeastern portion Of Lake Michi-
gan, not because they are the largest
or the most conspicuous in the world.
but because they are the most acces-
sible and the best known to the
people of the United States. In some
respects a still more interesting belt
of dunes occurs in western Nebraska,
stretching nearly across the northern
par N the state, approximately par
allel with the course Of the North
PlattVver. but at a distance Of many