Thanks. You pose many questions in your writing that question the origins of the geology you show in your excellent photos, even though at one point you say it is columnar basalt. This causes the reader to question if you really believe that fractures that formed during cooling was actually the source of what you can currently see today. So I wanted to direct them to a third party (inexact as wiki is) to help demonstrate physically sound, and well accepted cooling origins. Basically to perhaps draw the attention away from a potentially interested person in studying and understanding the topic from thinking that electromag was the main process here.

Futhermore there are many many earthquakes that these rocks experienced post cooling that did form additional fractures, those fractures that cut through and across the columnar joints, and these most certainly formed due to stresses in the system (earthquakes, gravity, tectonics). Sometimes earthquakes, which do occur and sometimes at large magnitudes in ID, are the main cause of uplift in the area. With lots of ideas out there, it is important not to get too distracted and stay as true as possible to the physics.

More info here with a great link to google earth files showing all the faults in idaho.

http://www.idahogeology.org/DrawOnePage.asp?PageID=73