Here’s a shot looking down on the conveyor belts that transported the gravel underground to the batch plant. It’s dated 9/15/1958. There is a hand-written caption on the back that reads, “Concrete batching plant and concrete aggregate piles. Aggregate goes to tunnel and conveyor belt below piles and took to top of plant.” If you enlarge this and look close, you’ll see a gravel truck approaching what I believe is the dump hopper.
On the right side of the photo near the top, you can see where the canyon wall has been excavated in preparation for the dam. You can also see the spillway cut out on the far side of the canyon. You can also see the anchor point for the bridge arch on the Page side. Just to the right of this picture is the present day Visitor’s Center.
You can also see the footbridge and its shadow being cast down the canyon wall near the center of the picture.