Calumet Bluff, meeting with Yankton Sioux — Patrick Gass: September 1, 1804

lightning and rain, which continued about two hours. We set
out early in the morning, along the north side of the island:
there is handsome prairie land on the south. Three of our
men went on the island to hunt. When we landed for break-
fast we heard several guns fired on the island, and saw six elk
swimming across the river about a mile above where we had
halted. Two of our men went up and killed one of them;
those on the island killed three. About twelve, the wind blew
so hard down the river, that we could not proceed, and we
landed on the north side, where there is an extensive prairie.
It was cloudy and rained till 4 when it cleared up. We re-
mained here for the night and dried our meat. On the bank
Opposite our camp is an ancient fortification or breastwork,
LEWIS AND CLARK EXPEDITION 27
similar to those which have been occasionally discovered on
the western waters. The two ends run at right angles to the
river, and the outside, which is 2500 yards in length, parallel
to it: there is no breastwork thrown up next to the river, the
bank as is supposed, serving as a sufficient defence on that
side.*