Exciting Archaeological Discoveries

So we're walking across our lawn and we see this:

Later that day we saw this:

We got really excited. The first stone could have been the random or accidental scrawlings of nature. The second stone implied "intentional" and hinted at some dawning awareness of numerical systems and order. Obviously, some nacent intelligence had visited our property at an earlier time

The clincher came on Day Three when I stumbled on the most important discovery to date:

Here was all the empiric proof we could have desired. Put in correct sequence, we now had 40-50-60. We are hoping beyond hope that our further investigations will yield "20" and "30" or even "70" and "80". Our fingers are crossed.