Baraboo weekly news. [volume] (Baraboo, Wis.) 1912-197?, 1912-08-08
The Geological Story of Devils Lake
Formation of the Bluffs Erosion of the Valley and
Coming of the Glaciers in More Recent
Times
By Samuel Weidmen, Geologist, Madison, Wis.

The region of Devils Lake and of the
Baraboo Bluffs, which extend ten to
fifteen miles both east and west of the
lake, is most interesting from many
points of view. The lake nestled at
the foot of the high rock cliffs that
rise 500 and 800 feet above, is bit of
scenery which is j lstly famous over a
large part of ouL country The entire
| region of the Baraboo Bluffs, of which
the immediate vicility of Devils Lake
| is but small part, is undoubtedly one
of the most attractive regions in the
Mississippi Valley for beauty of
scenery.
The picturesque scenery, further
more, has an in eresting and varied
hist ,ry quite unique among the geo.
| logical and geographical features of
our country. Few other areas of equal
extent contain so many points Of strik-
ing geological interests so plainly ex-
hibited. Among men of science, there
| fore, this is one of the most interesting
localities for the study of geology and
geography. Not only is it place for
student classes in our near by univer-
f., sites, but it is also of sufficient inter
est to attract learned men from abroad.
The Geologic Chapters.
In very general way the geology
can be divided into three parts. The
first part, a most ancient geologic
chapter, is the history of the great
ridges of quartzite which rise so alb
ruptly above the lake and which ex.
tend for ten and fifteen miles beyond,
to the east and wes', and which stand
so boldly above the lower lands to the
north and south.
o The second part, also quite ancient
chapter, is the history of the sandstone
which underlies the lower plain about
the quartzite ridges and TANKS and
overIies the bluffs at various points
along the slopes.
In the third part is included the rec
ords of relatively recent events in the
history of the earth, namely the gla-
cial deposits which lie in considerable
abundance a short distance to the
north and to the east of the lake. There
are still other portions of the history,
also, which are read from the coDfigu-
ration of the surface, rather than from
the rocks themselves.
The first part of the history, namely
that relating to the quartzite bluffs,
whose angular boulders lie against the
cliffs about the lake, takes us back to
the very earliest chapter in geology.
T e quartzite rock itself consists of
grains of sand in stratified beds,
which, while they now lie in titled
position, were originally deposited in
a horizontal position in the shallow
bottoms and along the shores of the
sea. A striking oft of evidence of the
water deposited character of the quart
zite is furnished by the ripple marks
in the rocks, made by the waves of the
ancient sea as the winds and the cur
rents moved the water back and forth |
along the shores.
Sand Tile Deep.
Into the sea, therefore, which is the
mother of all great sedimenf airy strata,
the grains of sand were gathered and |
an enormous thickness of sandstone |
was deposited. so far as our investi.
cations can show--and they seem to
be conclusive-the sand accumulated
in this ancient sea to a thickness of
something like 5000 feet, approxi
mile deep. At no time, how
ever, was the water very deep, for the
sea bottom sank but slowly, the depo-
sition of sediment approxim ateIy keep
ing pace with the sinking of the land
This formation of sand was laid upon
a granite basement below and was fol-
lowed by a deposite of shale or
slate which in turn was followed by
a deposit of iron bearing rock
in which the iron mines of the Bara-
boo valley are located. The iron
formation was later followed by a
thick deposit of limestone. These
later formations of slate, iron forma-
ton and limestone occur wholly with
ia the low land in the Baraboo valley,
and only the quartzite originally de- ,
posted as sandstone is to be observed ;
in the immediate vicinity of the lake ,
and in the quartzite ranges. ,
The Sea Bottom Mas Elevated. {
After the various strata of sandstone, !.
YSsS /