Wednesday, April 20, 2011

Mirage on the Desert

The bluish Bovine Mountains about 8 miles north of I-80 and, to the far right, the white, snowy Mount Harrison, a 9265 foot-high peak in Idaho, more than 60 miles north of Interstate 80 ... all behind the much closer Floating Island ... as seen across the mirage of the Great Salt Lake Desert, April 3, 2011.

When crossing the Salt Lake Desert from east to west, as came to pass on both trip one and trip two, we eventually came to the place where the salt flats to the north are not blocked by dikes of dirt or water control bars along I-80. The dikes disappear less than two and a half miles east of the northern rest stop near the Salduro railroad siding. At that point, uninhibited views of the vast desert appear, and any mirage that has formed becomes completely visible, unblocked by the previous water control bars.

I've never seen the desert without at least a thin mirage.
Mirage: not only does it appear that you can see water or sky beneath the dark, semi-detached island, but a thin white line floats across just left of center and just beneath the dark island, crudely marking the top of the playa surface (click to enlarge).
Floating Island (right) begins to detach from the Silver Island Mountains (left).
The white mountains to the right of Floating Island in this photo are the Raft River Mountains (of core complex and detachment fame).

The mirage of the desert causes the islands, large and small, to become like Rorschach tests, changing constantly with the lighting and the change in view angle resulting from our 70 mph speed. An appropriate name: Floating Island appears to float away from the Silver Island Mountains as you drive east to west; it also appears to float above the playa surface.
Floating Island can be seen clearly from the northern of the two Salduro siding rest stops. The dark line across the playa, above the white band where the sun is lighting up the ground, is probably a water bar, dike, or raised road protecting either the northern rest stop or the Bonneville Salt Flats racing area (the curved dike on MSRMaps). The apparent height of the dike may be enhanced by mild mirage, and some apparent lack of view of the lower part of Floating Island may be due to the curvature of the earth across 2.5 miles. The theoretical horizon distance for a short person like me is about 2.7 miles without considering refraction, and about 2.9 to 2 miles with a "normal" amount of refraction and no mirage, which will extend how far a person can see. Read more here.
Mirage and Floating Island pictures are all from April 3, 2011.

Related Posts:
Salt from Bonneville Salt Flats
A Tale of Two Trips

Last updated April 26, 2011. Corrections made to properly identify mountains in the distance.

8 comments:

helena.heliotrope said...

I had no idea you could take pictures of mirages. Or that they were so solid looking. Or that they actually existed, and weren't just hallucinations.
This kind of just blew my mind. I now have a new summer goal: see a mirage.

Silver Fox said...

And this was really a mild mirage!

Garry Hayes said...

You've always been looking for detachment...looks like these islands finally detached from the crust! Nice shots!

Evelyn Mervine said...

Wow! Enchanting.

Silver Fox said...

Garry and Evelyn, thanks!

I didn't realize the Raft River Mountains were in the picture until I looked on a map - hence the detachment theme. :)

Utemike said...
This comment has been removed by the author.
Utemike said...

Thanks for the post. Salt flats are nearly a commute for me. If you need to take a break from the highway, take exit 3 straight north to the Silver Island Scenic byway that loops the mountains and returns you to the exit to continue your drive.

Silver Fox said...

Utemike, thanks for the comments. After more careful review of Google Earth, the bluish mountains in the first photo appear to be the Bovine Mountains, with Mount Harrison being the white, snowy mass to the right. The Raft River Mountains are the white mountains to the right of Floating Island in the 4th picture. Doesn't make for quite as good an opening line, imo, but oh, well. :)

I do hope to take the scenic byway sometime, although I don't make it over there too often.