I've posted about Rock Island before, but I wanted to add some perspective. Above is a screen shot from the Republic serial "The Perils of Nyoka" (1942) that shows Rock Island in the background (near the top of the photo, just left of center), apparently filmed from somewhere near the top of Nyoka Cliff. The prominent rock figure near the center of the photo is Doglips. Not quite as easy to spot, toward the left side of the photo, is Lone Ranger Rock, at about the same height as Doglips. The top of Lone Ranger Rock is dark, and it has a round, lighter-colored rock that looks as if it's right on top of it but is actually an unrelated rock that was behind it. The juxtaposition of Doglips, Lone Ranger Rock and Rock Island gives some idea of where Rock Island should be.
This is what the area looks like today, not from the exact same spot as the "Perils of Nyoka" shot but as close as we could get. Click on the photo to see a larger version. Again Doglips and Lone Ranger Rock are the key markers, with both of them near the center of the photo. Today Redmesa Road runs through the area, providing access to a condominium community, the start of which can be seen in the top right corner. We've gone over the area many times trying to pinpoint Rock Island, and it's not as easy as it looks. I first suspected that some of the rock fragments on the west side of Redmesa, visible at the top of this photo, just right of center, were what's left of Rock Island. But a subsequent theory puts some of Rock Island in what is now the swimming pool area of the condos (not visible in this photo, but just beyond the top right corner). The 1952 aerial photo pretty much substantiates this theory.
This post provides a little better look at Rock Island.