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EarthCache

Holes in the Devil

A cache by Zemmy
Hidden : 9/8/2009
In Wisconsin, United States
Difficulty:
1.5 out of 5
Terrain:
4.5 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:


Holes In The Devil

 

WARNING!: You must be in good physical condition to attempt this cache. The trail is steep and the rocks can be slippery.

 

 

 

You will need:

  • Your Camera

  • A measuring tape

 

 

Devil's Lake State Park’s bluffs are part of the Baraboo Range, which scientists believe were formed 1.6 billion years ago, making them one of the most ancient rock outcrops in North America.

These ancient hills are formed of quartzite rock, which consists of grains of sand tightly cemented together.

According to geologists, the sand was deposited by rivers as they drained into shallow seas covering this area a billion years ago. As the sand accumulated, it first formed sandstone (a porous sedimentary rock) and then, under great heat and pressure, became quartzite (a non-porous metamorphic rock).

 

 

The Ranges Rise

Some time after the seas withdrew, the quartzite was buckled upwards in such a way as to form the North Range and South Range, with a depression between the ranges. The depression was filled with rocks softer than quartzite.

The area was then dry ground for a very long time. During this period, the Baraboo Valley was formed as the soft deposits in the depression eroded away. Many gorges were cut by running water during this period.

 

Underwater Again

Devil's Doorway was created by water freezing and thawing in cracks in the rock.

New seas re-invaded this area and their sediments accumulated on the land outside the Baraboo Hills, on the sides of the quartzite ranges, in the gorges, and eventually on top of the Baraboo Hills. The gorges were thus filled and the bluffs completely buried under sandy and limey deposits.

After the retreat of these seas, an ancient river or rivers removed most of the sediments from the Baraboo Hills and the surrounding area, thus exposing the quartzite bluffs again, and reopened the Lower Narrows Gap and the Devil's Lake Gap (these gaps may have been partially cut when the Baraboo Valley and the gorges were being formed).

Exposed outcrops of the quartzite that weren't covered by the glacial ice pack were subject to freezing and thawing conditions. Water seeping into cracks in the quartzite expanded as it froze and eventually broke pieces of the bluff away.

The thawing and freezing cycles also formed the piles of broken rock called talus on the slopes of the bluffs.

 

 

The Ice Age

The final chapter in this fascinating story took place about 15,000 years ago, when a sheet of ice (the Wisconsin Glacier) crunched into this area. The glacier covered the eastern half of the Baraboo Hills with ice but not the western half. We know this because its outermost boundary is marked by a ridge called a terminal moraine. This ridge consists of rocks and gravel dropped by the glacier as it stood and melted along this boundary.

The Wisconsin Glacier rerouted the ancient river(s) elsewhere and deposited dams of rocks and earth at the two open ends of the Devil's Lake Gap. These damps are part of the terminal moraine. Devil's Lake therefore is between two glacial "plugs" in an abandoned valley of an ancient river.

If there had not been a Wisconsin Glacier, presumably the ancient river(s) would still be flowing through the Lower Narrows and Devil's Lake gaps, and there would not be a Devil's Lake.

The lake is spring-fed and varies in depth from 40 to 50 feet. It measures 500 feet from the lake to the top of the quartzite bluffs.

 

 

The Task

From the Potholes Trail that extends from the top of the East Bluff to the beach area at the southeast end of Devils Lake you can see a number of well-formed potholes. Stones moving within the bottom of a long-lived river eddy drilled these cylindrical holes into the quartzite along the walls of the gorge. Geologists do not know if a glacial or preglacial river carved the potholes. It is known that rivers flowing from glaciers do carry large amounts of coarse sediment and commonly form potholes where they spill over bedrock. Non glacial rivers can form potholes as well, however, and because of no evidence that a glacier ever advanced to a position where it could have spilled melt-water over East Bluff in the vicinity of the potholes, it is thought it more likely formed by the preglacial river that carved the gorge.

 

Ground Zero can be reached from either the East Bluff Trail above or the Grottos Trail from below. (see map, click for larger version)

 

 

 

 

Logging Requirements:

#1 There is a pothole a few feet north of the coords that has some initials in cement, email the diameter of the hole and the initials. 

(Please do not post a picture that contains the initials)

AND

#2 Upload with your "Found it" log a photo at the pothole with your GPS

 

Not meeting the logging requirements will result in log deletion with out warning.


References:

Dott, Robert H. Roadside Geology of Wisconsin. Missoula, MT: Mountain Press, 2004

http://www.dnr.state.wi.us/org/land/parks/specific/devilslake/nature/geology.html

 


The Geocache Notification Form has been submitted to the Wisconsin DNR. Geocaches placed on Wisconsin Department of Natural Resource managed lands require permission by means of a notification form. Please print out a paper copy of the notification form, fill in all required information, then submit it to the land manager. The DNR Notification form and land manager information can be obtained at: http://www.wi-geocaching.com/hiding

 

 

Congratulations to Bus42 for FTF and making it back alive!

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Inventory

There are no Trackables in this cache.

 

Find...

180 Logged Visits

Found it 175     Write note 4     Publish Listing 1     

View Logbook | View the Image Gallery of 174 images

**Warning! Spoilers may be included in the descriptions or links.

Current Time:
Last Updated: on 4/20/2014 6:17:18 AM Pacific Daylight Time (1:17 PM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum