A chisel in the hand of God.

Via Neatorama, the story of one incredible hoax:

A Professor at the University of Wurzburg in Germany was fooled by his colleagues in the 18th century. They carved limestone into animal shapes and carved the name of God on them in various characters and hid them on a nearby mountain where Professor Beringer liked to hunt for fossils. Beringer became convinced that the carvings were actually created by God himself. Even when people pointed out that the limestone showed chisel marks, he held to his theory and even published a book on the stones.

Doing a little more digging lead to this site, where more information (and lots of images) was available. An excerpt:

Current wisdom puts the number of these bogus fossils produced (over a period of less than a year) at around 2000. It has been estimated that a single carving may have taken up to 6 hours to make. This was a serious stunt. And Beringer fell for it so completely that even when it was overtly put to him when he was preparing a book on the subject that the fossils were fake and had been produced in recent times, he refused to accept this as a possible explanation.

You can see in the above illustrations from the very very rare 1726 first edition of 'Lithographiae Wirceburgensis' that the stones not only included impossible soft tissue elements in the 'fossil' outlines, but that some of them included impressions of comets and the sun and even hebrew and arabic text!

And as it is put in the Wikipedia entry on Beringer:

The mechanism by which fossils were formed was not known at the time, and so despite the fantastical nature of these fakes Beringer took them seriously and published a book describing them. To his credit, Beringer took a relatively rigorous and scientific approach to the matter; he proposed several possible explanations for the fossils in addition to his own preferred interpretation, that while some few of these stones might be dead animals (fossils) most were just "capricious fabrications of God" hidden to test mankind's faith. He even considered the possibility that they were the carvings of prehistoric pagans, but he had to rule this out since pagans wouldn't know the name of God.

Even before publication of Beringer's book, critics had pointed out that some of the stones showed evidence of chisel marks. Beringer had noticed this too, and said in his book:

...the figures...are so exactly fitted to the dimensions of the stones, that one would swear that they are the work of a very meticulous sculptor...[and they] seem to bear unmistakable indications of the sculptor's knife... One would swear that he discerned in many of them the strokes of a knife gone awry, and superfluous gouges in several directions.

However, this evidence of sculpting only convinced him more strongly that the chisel was wielded by the hand of God.

Gotta love the power of faith to mislead.

Jim Downey