In this image we can see some of the elements we have discussed previously: the distribution of Havallah and related basinal (oceanic) sediments thrust onto western North America, the arc rocks accreted at the end of the Paleozoic and the dark blue arc accretionary prism rocks west of the arc. Note the termination of all these tectonic elements in the southwest U.S. (Courtesy of Prof. Burchfiel.)