Devils Tower

Well, I actually wrote this chapter a week ago but my internet connection was very poor and I couldn't save it so, here I go again and start catching up.

Devils Tower: many of you remember this from the movie "Close Encounters of the Third Kind". This is where I first heard of it. What a dumb movie. A grown man playing in his potatoes just like the little brother in "A Christmas Story". After the movie, I became acquainted with the geologic feature through one or more geology classes. It is about 60 miles from Newcastle so, I decided on one of the days that the drill was down to go and see it for myself.

There is an Indian ledgend about this land form. It tells about several Indian maidens who were out gathering berries or doing whatever maidens do. While they were gathering berries, a giant grizzly bear began chasing them. They prayed to the Great Spirit and he rescued them by causing a portion of the earth to rise up and lift them above the great bear and out of his reach. Anyway it is a pretty good story except I am left to wonder how they got down. The cliff is very steep. I may not have the whole story right.

Now on to the geology of the tower. The rock making up the tower is volcanic. It is a trachyte: a volcanic rock composed chiefly of alkali feldspar containing little quartz and plagioclase. As you might see in the picture, there are columns of rock. These are formed as the magma cools and forms 4, 5, 6, and 7 sides columns just as when mud dries there are usually 5 sided columns. There are two theories as to what it really is: one suggest that it is the eroded remnant of a laccolith much like the Henry, La Sal, and Abajo mountains of southern Utah, the other theory is that it is a erosional remnant of a volcanic neck. I like the old volcanic neck. The columns comprising the tower appear to be coming from a vent. There are volcanic flow structures with solidified columns in the San Juan Mountains of Colorado. I have seen other flow structures similar to this. It would be interesting to visit Ship Rock, New Mexico and see if the old volcanic neck remnant there is similar to Devil's Tower. Then again, each volcano is different and depending how deep the magma solidified would determine how quick it cooled and this may or may not have formed the column structure seen in the tower land form. Probably discussed it too much.