Hello Walt
I did not want to get into the kind of detail you did as it brings on expressions of bewilderment from some posters, consequently, I kept my reply simple.
I think we may disagree on one or two points, but that really is not important, as you know, many geologists disagree with one another, as do engineers, architects, doctors, etc. For example glaciation experts disagree on the boulder rounding issue and certainly neither you nor I are experts. I have read and discussed both theories with experts and whether water or ice, boulders if made of soft rock, will be ground to dust long before 60 million years have passed.
Yes conglomerated rock will spald along the perimater of clasts and depending on the concretion of the clasts you will get roughly equal spalding but you will also get roughly equal air-born water and wind errosion if the boulders were exposed. But supposed they wern't. Suppose they were burried for the majority of the last 9,000 years under soil or water, and only exposed over the last 1 to 2 thousand years. The isostatic rebound of the craton has been significant over the past 10,000 years, even 2,000 years. This was certainly a much wetter environment 2,000 years ago and the lakes, much larger. Hudson's Bay has moved east some ten to fifteen miles and the land risen, what is it, some 30 feet or more (I don't have the exact data in front of me) over the past 2,000 years. Considerably more over 10,000 years.
With simple wind and water errosion in a south Canadian climate, I believe the theory is 1 foot erroded or deposited for every 30,000 years. That would be approximately 2,000 feet of errosion or deposition in a typical climate since kimberlite emplacement.
However, the forces at work on this craton could hardly be classified as typical.
I spoke at length with another expert just a few weeks ago who informed me that they had traced as many as nine different ice directions in the general Snap Lake area, and these were just the latest glacial grooves not erroded by the last ice age of which we have had quite a few.
What is my point? Precisely this. The forces that have been at work up here are myriad and still not well understood. Pehaps they never will be. Certainly, their interrelated implicatons are only begining to be and some armchair theory about rough boulders equating to proximity to source is wholey simplistic and misleading to readers and investors.
As you say, "a little information can be misleading" but most certainly misinformation is....... and perhaps more so.
My two cents.
Regards |
