[inquest]

For example the digits of PI carved into a rock face on mars would immediately imply artifical, as lots is known about geology, and carving, and nothing we know could come anywhere near explaining such a thing.

And that's what distinguishes this from your rainbow example, where lots was not known about atmospheric science and optics at that time. I think that if the main contention of the ID'ers was correct, namely, that the features and diversity of living organisms could not have come about through naturalistic processes, science would be capable of determining that, at least with a high degree of probability.

[bobdsmith]

and it has...