See the context of this sign.

Unkar Delta

The broad, sandy expanse on the north bank of the
Colorado River is Unkar Delta, composed of rock
debris carried from the North Rim by Unkar Creek.
Prehistoric Pueblo people occupied numerous sites
on Unkar Delta and along Unkar Creek for about
350 years (A.D. 850 to A.D. 1200)

With abundant water nearby, Unkar Delta provided
a convenient home for these prehistoric people,
particularly in winter. Prehistoric remains on Unkar
Delta include dwellings and evidence of agriculture.

Prehistoric ruins on Unkar Delta
(below). Archeologists suspect that
Unkar Delta was occupied primarily
in winter, with many occupants
moving to cooler sites on the North
Rim in summer.

Don't miss the rest of our virtual tour of Grand Canyon National Park in 10803 images.