John Harrington and I as old men have had the memories of childhood experiences of knowing that we knew more about something than our fathers knew. Harrington said, “It marks the moment that I began to trust my own judgment in matters of what does and what does not make sense.” p. 34. He soon launches into several pages of how one develops straight forward reasoning which is based, in part, on Conan Doyle’s detective Sherlock Holmes. In essence, “Draw the least astonishing conclusion that can be supported by the known set of facts.” and “Understanding is knowing enough about something so that each part of it is seen in proper relationship to every other part and to the whole thing.”
Dance of the Continents – Adventures with Rocks and Time by John Wilbur Harrington is a classic popular book for the philosophy of geology. It begins with an analysis of what makes looking at old rocks so exciting to geologists and why it is important. He then explores what geological thinking consists of and how geologists go about finding and making sense of what information they can gleaned from what the Earth supplies. As an illustration of this process he takes us to a valley in Scotland named Glen Tilt (page 50) (56.828125, -3.785209) and shows us the jumble of rock that one of Geologies founding fathers, James Hutton, saw in 1785 at (page 52) ( 56.885844, -3.674484). You can go there on GoogleEarth and zoom into these exact locations and tilt the view and see quite a bit of what Hutton and Harrington saw which was an interface of two very different types of rock. To make the story more complete Harrington, seen in the photograph, is wearing the famous Sherlockian style, Deer-stalker hat.
He takes three of the heros of Geology, Louis Agassiz, Charles Darwin, and Alfred Wegener, and explores, not only what they found, which is usually all that is presented in text books, but also their reasons for looking where they were looking and what they hoped to find there. On page 106 is a photograph of a river worn rock that shows the passage of time quite clearly. It is a conglomerate rock made up of older conglomerate rocks that have embedded in them a much older conglomerate rock which with in that earlier rock has an embedded rock. In this single artifact we see four generations of rock each of which took a very long time to form. What a wonderful rock he had found. I carried a piece of Hutton’s Rock from Edinburgh, Scotland in my pocket for seven years until last month when it vanished. It was an unusual rock but it required some explanation to show its value. Now I want to find a rock of many generations like the one shown in the illustration because it is self explanatory. It shows much of the history of the Earth in a hand held stone. So much has happened in this world of earth, weather and time! It is summarized nicely by Robert Frost’s, Sonnet – Once by the Pacific.
The shattered water made a misty din
Great waves looked over others coming in,
And thought of doing something to the shore
That water never did to land before.
The clouds were low and hairy in the skies,
Like locks blown forward in the gleam of eyes.
You could not tell, and yet it looked as if
The shore was lucky in being backed by cliff,
The cliff in being backed by continent;
It looked as if a night of dark intent
Was coming, and not only a night, an age.
Someone had better be prepared for rage.
There would be more than ocean-water broken
Before God’s last Put out the Light was spoken.