In my post from May 22nd ("Tioga Pass is Open") I talked about how telephoto lenses can flatten perspective and create abstract patterns. Wide-angle lenses are perfect for creating the opposite effect—a sense of depth in a flat, two-dimensional photograph.
Wide-angle lenses make everything look smaller and further away. They also expand space—they make objects look further apart than normal. You can take advantage of this by exaggerating the size difference between foreground and background to create an illusion of depth. You must get close to something in the foreground, as I did with the rock strata in this photo from Zion—otherwise everything will look small and distant. It also helps to include converging lines, like those in the foreground rocks, to create a sense of perspective. Often a vertical orientation works better than horizontal as you can include a bigger sweep of the foreground.