Unfortunately, your question is somewhat unclear. Do you mean "stone" or "image"? If so, this part of the story comes after John has had his dangerous rafting experience and has arrived at the Place of the Gods. He is full of wonder at what he is seeing and is trying to interpet all that he can see, but without success. Note the repetition (three times) of the phrase "How shall I tell what I saw?", which seems to capture John's amazement and bewilderment at all that he can see as he views vestiges of a former civilisation that has meaning to us as readers but leaves him ignorant. John comes across a shattered stone and also a broken image of a man:
I saw a little dance of white butterflies over a great heap of broken stones and columns. I went there and looked about me - there was a carved stone with cut-letters, broken in half. I can read letters but I could not understand these. They said UBTREAS. There was also the shattered image of a man or a god. It had been made of whtie stone and he wore his hair tired back like a woman's. His name was ASHING, as I read on the cracked half of a stone. I thought it wise to pray to ASHING, though I do not know that god.
In this description we see another example of the gap in narration. The first person narration allows us to see that John has never heard of who he interprets to be the "God", ASHING, whereas we as readers from our time identify the figure as George Washington.