intraplate ring complexes, Air, Sahara: Fitton 1

A river of basalt lava river snakes down the flank of Kilauea Volcano, Hawaii, in this nighttime scene. Low clouds reflect the glow. Fire and smoke in the distance show where the flow has entered forest. Mauna Ulu eruption, February 1972, photo by Warren Hamilton. Hamilton 1

Yemen Traps (Oligocene flood basalt) at crest of the Red Sea shoulder uplift, southwest Saudi Arabia near the Yemen border, summit altitude ~2500 m. The basalts correlate with early opening of the Red Sea near the Afar triple junction, and in conventional plumology are thought to have erupted upon a greatly-uplifted region. However, the basalts overlie more than 100 m of laterite and saprolite (pale colors), developed over tens of millions of years from Proterozoic granite, preservation of which suggests that eruption preceded uplift and that no plume was involved. Photo by Warren Hamilton; Hamilton 2

Diabase sheets of the Jurassic Ferrar large igneous province, Antarctica, intruded into late Paleozoic sandstone that is coal-striped in its upper part. Each sill is about 300 m thick. The lower sill is concordant to bedding, and sends an offshoot into its floor. The upper sill rises obliquely through the lower sill, and flattens into concordance at top of cliff. Finger Mountain, Royal Society Range, Transantarctic Mountains. Photo by Warren Hamilton. Hamilton 3

Lithospheric instability