The harbor of Grand Marais, named by the
French meaning “Great Marsh”, is the result of unequal weathering
or erosion of rock. One of these, called diabase, resulted from the
cooling of molten material which was forced between two earlier
lava flows. The dark massive diabase, being very hard and resistant
to wave action, has become the outer barrier to the harbor, while
the lava, which was much fractured and easily eroded, was worn away
to form the harbor basin.
To the west of Grand Marais, the serrated
crest of the Sawtooth Range, clearly visible from the harbor
breakwater, is another example of unequal erosion. Here the
relatively soft basalt and the more resistant diabase have, through
the process of weathering, produced the notched profile of the
hills along the coast.
To the east of Grand Marais rise the hills
near the mouth of the Arrowhead River, while
to the north along the Gunflint Trail are older rocks. At Saganaga
Lake, the Saganaga
Granite, one of the oldest granites in North America, marks a core
of the ancient mountains of the Laurentian Highlands.
Historical Information
The Grand Marais Harbor Lake Superior Indians recognized the
unique nature of this bay long ago, naming it 'Kitchi-bitobig',
meaning 'double body of water.' When white man first settled around
this bay, in 1854, a few Indian families lived in tepees and cabins
around the shore. White population increased rapidly after the
1870s, and dependence on ship transportation became more critical;
storms and shipwrecks led to demands for a lighthouse, which was
finally built in 1885, the first on the American north shore. As
added protection for this harbor of refuge, the east breakwater had
been built a year earlier; the harbor became even more protected
from violent seas in 1901, when the Corps of Engineers completed
the west breakwater and continued the 16' dredging project. During
three generations, this bay was a busy hub of economic and social
activity: commercial fishing, shipping and rafting of sawlogs and
pulp wood, dredging gravel, picnics and bonfires on the point, 4th
of July celebrations, skating and swimming, sailboat races, the
arrivals and departures of the steamships 'Dixon' and 'America' and
many other vessels. Until the new highway along the North Shore was
built in the 1920s, this magnificent harbor was the focus of life
in Grand Marais.
TO LOG THIS CACHE:
1) How many types of rock were eroded to form this harbor?
2) Record the harbor shoreline surface water temperature.
To log this cache E-mail me
HERE.
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