Sunday, April 10, 2011

TW3 - Angle of Repose

Angle of Repose for Sand dune
My last blog here was about cascade failure. It is one of my favorite scientific theories. Others include Chaos Theory, Queuing theory, and paradigm shift. And the subject of this blog: Angle of Repose - in short you can only pile sand (or shit or any other substance) only so high. (Note: the precise angle of repose varies per substance and moisture content but more of that later.) I choose sand as my illustration here because as children this may be our first encounter with the laws of physics as we sit in our sandboxes with our pails and shovels.

I noted in a recent local news article that the Questa Moly Mine is putting off clean up of waste for 18 years. This is relevant to our topic because it has piled slag and dirt from its above and below ground mines to beyond the angle of repose. This is possible by misting the piles to solidify them. And it works for a while. Erosion by rain and wind can steepen that angle artificially beyond the natural angle of repose. Then you just add water and shake and landslide.

Clarksville, Arizona
A lot of mining areas are in geologically unstable areas. So an earthquake can provide the shake rattle and roll, and a good heavy downpour the water. It this happened at the Moly Mine it would dam the Red River and back it up into the town of Red River because the slag pile is right by the highway which runs beside the river.

The wetter a substance is lesser the angle of repose. Example shit as in produced in the recent congressional sessions about budget. But an interesting thing happened here in that the light shone on to the ever growing pile by the news media seemed to make it possible to only pile it higher. Where is a fire hose when you need one? I propose we move our nation's capital to the San Andres Fault in California for the shake factor in collapse.

My week? Well, a bit like the return to that sand box. I get my savings piled just so high and something makes it all collapse. In this instance car repairs. And I didn't even shake my piggy bank.


  1. Your comparisons are mind blowing. There is never a fire hose when you need one in the same way that there is never a bus when you need one - and then they all come at once!


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