Various sized discolored circles were found in the backyards of houses in our subdivision using Google Earth. These were found on a map of Google Earth/Apple Maps taken in 2011. They are no longer can be seen on the new maps of Google Earth! We have checked quite extensively for other circles in the surrounding area where we live and found no other circles. I do not think they were caused by fertilizer, watering, springs, etc. As you can see they are of varying size and density of color. I measured those in my backyard and they were approximately 28 ft. in diameter. Please let us know what you think they could be! Thank you! P.S. I have higher resolution images if you need them. Taken with new I Pad through screen shots.