It's the build up of salt in the evaporation ponds, the salt water wells up out of a spring beneath the mountains and spills out of the mountainside to constantly fill the ponds at an elevation of 10,000' ASL.

You can just make out the stone stairs that protrude from the walls of each tier. I am sitting on a similar set in the pic below.

@Surfpirate very cool! How tall are the rings?

@Donna_I I would guess they are about 8' tall. The site is on privately owned land so you can't walk down to it unless you are part of a tour. We hired a cab for the day and got to see a bunch of things that were not on most lists, including a fabulous meal at a tiny resto that served Inca cuisine, I had the Alpaca.

@Donna_I We wound up driving over a small foot bridge that was crowded with people carrying all manner of stuff, our driver just pushed his way through even though the bridge was no more than 8' wide and the length of a football field over a river. We wound up at this little resto in a small town in the middle of a residential area. The Alpaca was delicious, the yellow potatoes were very different and tasted like yucca and the eggs were from guinea hens.

@Surfpirate sounds like that trip was equal part terrifying and fabulous!

@Donna_I The roads were the most dangerous part of that trip, nobody drew a gun on us at all during the 2 years we were in South America, pretty tame compared to some of our other adventures. lol

@Surfpirate two years is quite a trip! What were you doing?

@Donna_I We were looking for someplace to build and semi-retire, almost settled in Ecuador but changed our minds after a year, learned some Spanish, saw a lot of stuff, met a lot of interesting people and had a lot of fun.

@Surfpirate wow! south america is on my bucket list.