Amongst the superstitions mentioned by him, none caused more attention than those connected with the worship of their Spirit rocks. One of these, which has always been considered to be an important Manito, happened to be on the plateau above Mendota, and the Indians directed me to the spot where it was placed. I found it to be a huge granite boulder, which had probably been deposited there by the moving waters or icebergs, during that remote period when they were travelling southwards from the sub-arctic latitudes. As it had no geological relation whatever with the sandstone ground upon which it rested, the Sioux might have conjectured, that it had been dropped from the clouds. To ignorant savages, unversed in the mysteries and conclusions of scientific geology, no other explanation could have been satisfactory. It lies upon a level space of land, upon the top of a bluff, commanding magnificent views over the valleys of the Mississippi and Minnesota. The confluence of these great rivers can be seen, and the steep water-worn cliffs below the falls of St. Anthony. Whilst standing upon the promontory, and looking at this wide prospect, I was joined by a priest, who had been fulfilling his duties at a neighbouring settlement. We remained near the Spirit rock,[35] looking at the solitary mass of granite, glittering in the sunshine, and thought that it was not surprising that the Indians believed this strange rock to be the manifestation of a great unknown power, and should have invested with supernatural attributes what must have seemed to them to be marvellous. The boulder is polygonal in form, and stands about seven feet high above the ground. In the other dimensions, it averages a thickness from nine to twelve feet. It is composed chiefly of grey granite, and its weight must exceed seventy tons. Faribault said that, when he was a young man, wandering bands of Sioux occasionally came to this Spirit rock and encamped near it. They usually stopped about a week, but sometimes during a whole moon. It was their custom during this period to continually offer sacrifices, dance round the stone, and paint it with various colours, red, blue or white. Finally, before taking down their tents, they covered it with their best furs or skins, and left them there as propitiatory offerings. [Illustration: SPIRIT ROCK. CONFLUENCE OF THE MISSISSIPPI AND MINNESOTA.]