31 October 2010

Ch 2 : "The Wrangell Formation," Pt 2 from "Legacy of the Chief"

The  Wrangell Formation, Pt 2
Wesley Dunkle  -- Chapter 2 of "Legacy of the Chief"

“Thank you, Mr. Benson.  It is indeed an honor to be here.  Class, let me give you a brief background on my professional life.  I came to Alaska in 1912 to work as a consultant for the Alaska Copper Company when the company which was the predecessor to Kennecott Copper Corporation began to try to determine the extent of the copper ore on its mine properties.  I worked along with such great men as Lewis Levensaler and Alan Bateman in developing a theory explaining the nature of the rich ore occurrences along what we called the Kennicott Formation.   We found that the ore was principally a copper sulfide and that it was much more extensive than originally believed.  This ultimately caused the company to acquire adjacent property it had originally rejected.  These were the Mother Lode claims. There is a fascinating story behind that.  I hope we have time today to pursue that story.
      “Successfully determining the probable lay of the copper ore became my main contribution to Kennecott. I later took a strong interest in the nearby Willow Creek gold district and ended up developing the Lucky Shot gold mine in 1928.  Those claims became the richest  in the district.   Now I’m working my own gold mine along the southern slopes of the Alaska Range in a mine I have optimistically named the Golden Zone.”
Golden Zone
Wesley Dunkle's Golden Zone Mine
      The engineer received several laughs when he made that comment.
      “But I came here to speak on the subject of the occurrences of Alaskan copper in the Wrangell Range.  So that is where we will begin.”
      Wes looked around at the the very young faces.  In the back of the room he spotted a much older Native man who seemed to resemble men he had met many years ago in Chitina. 
      “You, sir.  Have I met you before?”
      “Not likely, Mr. Dunkle.  My name is Johnny Gadanski.  I had a father who worked at Kennecott as a painter and carpenter when you were there, but you probably didn’t know him.  I grew up in Chitina and worked in the Mother Lode and the Erie mines while William Douglass was in charge.”
      “Really? What a coincidence! Johnny Gadanski is it?  I can’t say I recognize the name.  But what a privilege to meet one of the men who worked on the site in those early days.”
      “My pleasure, sir.  Working at Kennecott was one of those rare privileges I’ll always treasure.  I was lucky enough to have come to town a few days ago when I read in the paper you would be speaking here. You might say I’m revisiting the old mines.”
      The rest of the class was now looking at the lanky man who appeared to be in his mid-fifties.  It was rare to find an Alaska Native in a class such as this.  It was especially unusual to encounter a Native who had worked in a large Alaskan mine.
      “Class, this man, Johnny,  in the rear of the class has made a good point.  He lived a piece of history at a copper mine which is unique in all the world.  We are both privileged to have been a part of it.  It is unlikely we will see anything quite like the Kennecott operation  in Alaska again.
      “Thank you, Johnny.  My pleasure to meet you.
techtonics slide 1
Slide #1: movement of the Wrangellia composite terrane
      “Class, while the story of the copper seems to begin in the Wrangell Range of south-central Alaska, it is much more complicated than that.   The outstanding feature of the area is a series of mountains of  volcanic origin which include some of the tallest in North America.   The process of the formation of the earliest of these volcanoes began twenty-six million years ago as a result of the friction of one terrane moving into another.  Appropriately enough, we call this the Wrangellia Terrane.  The terrane began its long trek  from a place thousands of miles away,  much closer to the equator.  A terrane is a fault-bounded  area which has a geologic history distinct from its contiguous terranes.
       “The terranes move over a relatively fluid part of the earth crust deep below the surface called the asthenosphere.  The asthensosphere is the source of the magma which wells to the earth’s surface.  This process occurs along spreading rift zones or ridges, mostly in the ocean areas.  The rift zones separate the oceanic crustal plates.   New magma erupting along these ridges forces the older crust outward into the adjacent plates.  The older crust is then forced downward in a process called subduction by which the heavier oceanic plate plunges under the lighter continental plate.  The plates which specifically concern us are the Pacific plate and the continental North American plate. 
       “The theory of plate techtonics is very recent.  When we mining engineers at Kennecott developed our  hypothesis  regarding the origin of the copper ore, the theory did not exist.  For purposes of  predicting the likely lay of the copper deposits, however, it was not really necessary to understand the process.
techtonics slide 3
Slide 2: the process of subduction under the Wrangell Range
      “Before going any farther, I want to say a few words about my relationship to Kennecott Copper.   Although the district is worked out,  it was once heralded as one of the great copper territories of the world.  At the turn of the century men fought and even died just to hold the exclusive rights to a small number of proposed railroad routes which passed through the coastal range from Katalla, Valdez and ultimately Cordova.  Only a handful of feasible routes existed. The promise of rich copper in the Wrangells was enticing to say the least.  But only an enormous infusion of money could make it all work.  This was the catalyst for the formation of the Alaska Syndicate, which primarily consisted of the Guggenheim family--a mining and smelting conglomerate, JP Morgan--the railroad financier, Kuhn-Loeb Brothers, and the Havemeyer family who were the original backers of the great Stephen Birch.

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