We stopped at Isberg Pass briefly to rest and munch on some well-deserved snacks, having hiked roughly
11 miles to this point, including one moderate and one minor pass. I was still at the top of the pass while the
 others began the descent down toward Sadler Lake, near the center of the picture above, just a bit past our
destination for tonight. There was a gentle breeze blowing, which felt pleasant as it cooled my hot, sweaty body.

Suddenly, out of nowhere, came this tremendous noise, like the roar of a fighter jet engine. It sounded like it
was just twenty feet away. It was LOUD! And whatever it was, it was completely invisible!

It started moving around a bit- a little to the right.. then to the left.. and it was getting louder, i.e. closer! It now
seemed like it was less than ten feet away. All the time, it remained totally invisible! I was getting seriously
freaked! In the next instant, it passed right through me,  and was now behind me. Then it just ended.
 What the ****?!?!

I stood there for a moment, dazed, trying to determine if I had gone insane. I yelled out to the others, who had
just started the descent: "Did you guys hear that?". I think somebody answered back something like: "yeah, what
was that?!",  but it was hard to tell. The breeze was blowing just hard enough, first from one side of the ridge,
and then from the other side, to hear well.

Then the noise started again. It started at about the same place it had started the first time- about twenty feet
in front of me. Again, it moved - or danced or hopped? - around a bit as it approached me. This time it passed
just to my right as it went by, and then ended as abruptly as it had started. Again, it was a noise without any
substance; it was completely invisible! A few seconds later, give me a break!, another one started up.

I was still pretty freaked, but I was working on a theory: as the first two were moving around on their way
more or less toward me, I could on rare occasions see some of the scrub brush moving a bit in the general
vicinity of (though not always exactly at) the noise. The brush here was all pretty sturdy- the gentle breeze that
was blowing wasn't going to budge them. At first I thought that the moving brush was due to some
small animal(s), possibly as freaked by the noise as I was, trying to get away from it. I even briefly had
the nightmarish thought that the noise and the brush movement were actually due to some kind of invisible
animal (do you remember the movie Forbidden Planet?). This time I thought I saw a bit of dust kick up
around where the noise was. Yes, some dust kicked up and spiraled upward a bit. It was becoming clear.
The noises were Dust Devils!

Well, I have witnessed plenty of dust devils before (though never on a backpacking trip), but those gentle
swirls had nothing in common with these things. These sounded like the air itself was being ripped open.
They were loud- as I said initially, like a fighter jet flying nearby on maneuvers, which occurs quite
frequently in this area. Anyway, these things were packing a huge amount of noise for a vortex that, as
near as I could judge, was at most one foot in diameter.

I heard, and almost saw, a couple more of these as I was getting ready to head down. Then, about 30 yards
off to my right, I heard the mother of all of them. I could see plenty of dust, and even some smallish rocks,
swirling around this one. I had had enough- I decided to get out of there while I could, before I wasn't in
Kansas anymore, if you know what I mean.