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Basalt Column

A cache by Lotus72 Send Message to Owner Message this owner
Hidden : 2/12/2007
1 out of 5
1.5 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:

For cell phone users: (TASK 1) Choose 1 column and measure circumference of it (units r your choice) Explain how you arrived at the measurement! (TASK 2) The second task is to count the number of columns that start in the dirt- count from left to right. (TASK 3) take a picture and upload it to the geocache site showing a person with the columns behind. Answers to TASK 1 and TASK 2 are to be emailed, TASK 3 is to be uploaded.

Skinner's Butte!
It is a popular area for rock climbing and exploring the old volcanic history. The opportunity to touch and explore hexagonal stone columns is worth the journey. How does nature create such a geometric design in stone?

When traveling around Eugene and Springfield it is hard to imagine the area covered in hot lava flows, surrounded by erupting volcanoes and later having a bay lapping at the nearby hills. Our area has experienced all of these natural phenomena. Over the millions of years the volcanoes went dormant or extinct and the seas receded. In some places one can find sand and other evidence of the shallow bay that existed in our area. The more obvious evidence of the turbulent volcanic life exists in eroding volcanic mountains and hills and old lava flows, not to mention numerous other geologic items. In Eugene exists a ghost of the Miocene Era, one that ended with flood basalt eruptions covering many parts of the Willamette Valley.

The columnar basalt rocks are on the ‘old side’ of the Cascade Range. The columns are from a thick basalt flow that was later exposed while being quarried. The Columbia Plateau was built up by flood basalt eruptions that culminated in the Miocene, roughly about 15 million years ago. The Cascade Range has been slowly moving eastward, thus encroaching on the Columbia Plateau.

Looking at the basalt columns one can see the hexagonal jointing evident in each of the columns. Large volcanic eruptions can cause deep flows of magma. When this magma cools it sometimes shrinks a little bit, thus causing columnar presentations such as these. While the lava cools it contracts and cracks the rock into parallel hexagonal columns. While most of the columns have six sides (thus, hexagonal), some may have five or seven sides instead. The columns could have also crocks in another fashion, that of irregular fractures that are called ‘entablature’. The irregular fractures do not end up with smooth columns, but rather cracked large columns that are at an angle. This often happened when the basalt lava flows cooled quickly from the top and bottom, but the middle cooled at a different rate. The top and bottom usually formed columnar basalt outcroppings with some of the ‘entablature’ irregular pieces in the middle. As the Willamatte Valley has an ancient volcanic history, these columns are a modern reminder of a volcanic past. Humans have found these columns to be helpful as the city of Eugene started to be built. The quarrying starting in the 1890’s and continued through the 1930’s. The quarried basalt was either used as solid foundations or crushed into gravel at a nearby processing plant. Columns were used as foundations for structures and houses, walling and edging, and sculptures, etc. The basalt columns are part of Skinner’s Butte, a municipal park in Eugene, Oregon. The local Native American tribe, the Kalapuya, called it “Ya-Po-Ah”. The City of Eugene dedicated the park in 1914 and over the many years the park has been a camping spot, a zoo, and a CCC (Civilian Conservation Corp). It is now a popular spot for rock climbing as the columns rise a few hundred feet in the air. The entire park houses Skinner’s Butte, a small volcanic outcropping that rises 682 feet in the air.

IN ORDER TO LOG THIS CACHE: You must complete the following THREE tasks: -- please note that how you measure (units, etc) is vague and open to fun! This is meant to be fun and educational!

(TASK ONE) Choose one column and collect the GPS coordinates of a single columns as well as the circumference of the single column. You must explain how you arrived at the measurement! Just how you measure it is up to you... be creative! (TASK TWO) The second task is to count the number of columns that start in the dirt- count from left to right.This is also a bit vague, for a good reason. Where some start and stop is open to interpretation. Be creative! (TASK THREE) take a picture and upload it to the geocache site showing a person with the columns behind. The Answers to TASK 1 and TASK 2 are to be emailed, TASK 3 is to be uploaded.

Additional Hints (Decrypt)

Oevat n zrnfhevat gncr be bgure qrivpr gb zrnfher gur fgbar.

Decryption Key


(letter above equals below, and vice versa)



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