This is not a great photo, (I took it in a dark exhibit room at the White Sands Visitor Center) but it gives an idea of how the Tularosa Valley, where White Sands is located, formed. The valley (low middle section) was once a huge dome that collapsed 10 million years ago. The Sacramento Mountains are on the right side of the exhibit, they are 1000 feet higher than the San Andreas mountains on the left side. We saw the bands of rocks as we drove along the highways near Alamogordo. Some bands were horizontal, others were nearly vertical, proof of the incredible upheaval the area once underwent.