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Tuesday, 17 October 2017

Parable, analogy and the Irish Sea Glacier

In the bad old days, before the enlightenment and before scientists had been invented, Jesus Christ went hoofing about in Palestine doing his preaching.  Almost always he used similes, metaphors and especially parables to put his message across to his listeners, who were in general simple folk who had not had much in the way of education.  Most good stories, whether for adults or very small children, are also parables or allegories, sending messages about ethical issues or about "the truth of things" in attractively packaged formats.  I hesitate to compare myself with Christ, but I have found in the course of teaching university students and members of the public that there is no point in talking about landscape-forming processes involving glaciers or rivers or deserts if the listener does not have a mental picture of what these things actually look like.  Nowadays the level of awareness of natural phenomena is much greater than it was 40 years ago, because images are thrown at us all the time via TV, cinema, computers, tablets and so forth.  But the analogy still works, if I as a teacher want you, as a student, to understand what I am talking about.....

When I sit on a stone on a mountain top, looking down at a landscape below me, I instinctively recreate in my mind's eye what it might all have looked like when covered by ice, or partly submerged by the sea, or affected by tundra rather than deciduous forest conditions.

So I was rater chuffed the other day when I was idly scanning through (as one does) some NASA images from Antarctica, I came across an ice stream image in which showed two branches of an ice stream on the edge of the West Antarctic Ice Sheet. Between the two branches there was an ice-covered upland maybe 200 km long by about 50 km wide, and the western ice stream branch had a spectacular 90 degree bend in it as it swung around the outer edge of the upland.  Immediately I thought "Irish Sea Glacier and the Welsh Ice Cap!"

So here we are.  The top image is my latest recreation of the Anglian (?) glacial situation in SW Britain, and below it is something I created last night, involving image resizing, image superimposition, addition of colour, instant alpha, and adjustments in transparency.  I had fun!  The resultant image does not involve any horizontal distortion, so it is not a perfect match for that went on during that big glacial episode around half a million years ago.  You seldom get perfect matches in nature.  But it's near enough, with the main ice stream running down the western side of Wales and then swinging into the Bristol Channel, forced by powerful ice pressure from the west.  To the east of the Welsh uplands there is another ice stream, replicating the ice stream that came in across the Cheshire Plain and into the west Midlands.  And over Wales itself we see an undulating ice cap surface within which it is difficult to pick out individual glaciers or drainage routes.  That is probably not far off the way it was........

Isn't nature wonderful?


TonyH said...

Well co - ordinated, Brian. I distinctly remember saying to you in one of your Durham University Geography Department Tutor Group sessions [1968-69...... long, long ago] did you think there was a validity/useful purpose in making analogies in geographical studies!

Steve Hooker said...

Cool ;- )
Bet you're busy with the new high rez Antartica maps.