Since we're here I have a suggestion to offer. When submitting your mobile app to the App Store there is a checkbox/option somewhere asking you to if you want to distribute the app to Mac as well. DO NOT do that. If enough people do that we'll end up having a Mac app store walled garden powerful enough to extract its 30% tax.
Assuming the round circle was built of stones, plants growing over stones tend to develop stronger, more entangled roots. These plants become hardy than similar species of plants growing nearby over loose soil. Rock crevices also tend to accumulate water which these plants should be able to use when other adjoining plants are dying. I think this is the reason why the circle became apparent during this drought.