Wednesday, November 19, 2014

A Plate Tectonics Pioneer - Frank Bursley Taylor

To start off, I was going to say recently but it has apparently been almost a year now, but "recently" I came across this blog post by GSA entitled "On the Shoulders of Giants: A 125th Anniversary Retrospective" which talked about several of the older GSA members and geologists. There was one story which caught my attention:
 "In 1908, Taylor presented an oral paper at the GSA meeting wherein he proposed Continental Drift as a mechanism for the origin of mountain belts. His 1910 paper in the GSA Bulletin is spooky to read these days. He talked about the mid-Atlantic Ridge being a place where “plates” were moving apart. He talked about the Himalayas being the place where the Asian continent was being thrust out onto the Indian crust. He talked about the Aleutians being thrust out onto the Pacific Ocean floor. Taylor’s oral presentation was four years before Alfred Wegner’s oral presentation, and his publication was five years before Wegner’s. But, Taylor’s affliction was that he was publishing in an American scientific journal, and Wegner published in German.  Back then, if anything was important, it was published in German. So, most of the geological community is unaware of Taylor’s amazing analysis."
And it linked to a GSA Today article from July, 2005 which briefly mentioned the original Taylor paper. Well I wanted to go back and actually see what was stated in the paper 5 years before Wegner published his theories. Even though the paper is often painful to read, due to what we now know about plate tectonics, it is interesting in parts to see how much he got right. Here are some excerpts from the paper:

Taylor, F.B. 1910. Bearing of the Tertiary mountain belt on the origin of the Earth's plan. Bulletin of the Geological Society of America. v. 21. pp. 179-226

General crustal movement
"It is admitted by all that the mountains of the great Tertiary belt, like the older ranges of fold-mountains, were produced chiefly by compressive forces acting in a horizontal direction, and that the total amount of compression involved is equivalent to many miles of horizontal movement of the of the Earth's crust. What was the nature of those movements? In what direction did the crust move in producing the Tertiary mountains of Asia-from the ocean toward the land or from the land toward the ocean? This is a crucial point."
The Himalayas
" seems apparent that it was the obstructing action of the Indian peninsula which produced the great Himalaya re-entrant. It was the tremendous resistance offered by this fragment of the ancient Gondwana-land which held back the advancing folds to the line of the Himalaya. The effect seen in horizontal plan is as though India had held back an advancing curtain in a very pronounced way, as indeed it did, for the curtain was the crustal sheet of Asia."
He also refers to "moving crustal sheets" and "plates" are also brought up.
"It would be expected, for example, that the folds would be most closely pressed together at the most northerly point of the resisting obstacle, where the obstructing effect would be greatest, and that the folds would bend or lap around on either side of the obstructing mass so as to inclose it within a re-entrant angle of the general front. It would be expected also that the vertical component of movement expressed by positive elevation of mountain ranges and plateaus would be greatest against that same point."
Taylor seems to think that all movement was from the poles to the equator. This is what produced the bulging outward effect of the Earth at the equator.

Greenland Rift Zones
"Baffin Land, therefore, appears to have been pulled away from Greenland in the same direction as Grant Land, and, what is more significant, it appears to have moved the same distance."
"The relation of the coast of Labrador to the west coast of the south part of Greenland is truly remarkable"
"...although now 560 miles apart in the direction of the rift along the northwest side of Greenland, are almost exactly parallel and the geological age and structure of the rocks, so far as known, are the same."
"We seem to have here a great irregular rift line along which North America has been torn away from Greenland." 
Mid-Ocean Ridge
"It is apparently a sort of horst ridge-a residual ridge along a line of parting or rifting - the earth-crust having moved away from it on both sides."
 "The great westward bulge of Africa north of the equator appears to fit very closely into the westward bend of the mid-Atlantic ridge, suggesting that Africa has drifted eastward from that position."
"It is probably much nearer the truth to suppose that the mid-Atlantic ridge has remained unmoved, while the two continents on opposite sides of it have crept away in nearly parallel and opposite directions." 
African Weight Gain
"There appear to be conflicting evidences on this point, but the great rift valleys of the lake region in Africa suggest moderate uplift. These valleys are roughly meridional and suggest a slight girth-expansion of the Earth.

Not sure how the Earth gains girth... maybe too much Turkey. (ba dum dum :-D)

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