plate reconstructions the Pitcairn hotspots although not all point at a presently active hotspot. More than one hotspot may have influenced the growth of Resolution Guyot, and it and Allison Guyot may have been formed by the same hotspot(s). The entire Mid-Pacific Mountains may be the product of such a hotspot. Composition Rocks found at Resolution Guyot include basalt of the volcano and carbonates deposited in shallow-water conditions on the volcano. Minerals found in the basalt are alkali feldspar, clinopyroxene feldspar, ilmenite, magnetite, olivine, plagioclase, spinel and titanomagnetite; the olivine, plagioclase and pyroxenes form phenocrysts. Alteration has produced analcime, ankerite, calcite, clay, hematite, iddingsite, pyrite, quartz, saponite, serpentine and zeolite. The basalts represent an alkaline intraplate suite, earlier trachybasalts containing biotite have been recovered as well. The carbonates occur in the form of boundstone, carbonate hardgrounds, floatstone, grainstone, grapestone, oncoids, ooliths, packstone, peloids, rudstones, spherulites, and wackestones. Alteration has formed calcite, dolomite, quartz through silicification and vugs. Dolomite alteration is particularly widespread in modern atolls and several processes have been invoked to explain it, such as geothermally driven convection of seawater. Dissolved fossils and traces of animal burrows are found in some rock sequences with bioturbation traces widespread. Barite needles, calcretes, cementation forms that developed under the influence of freshwater, desiccation cracks and ferromanganese occurrences as dendrites have also been found. Organic materials found in rock samples from Resolution Guyot appear to be mainly of marine origin. Some of the organic matter comes from microbial mats and vegetated islands, including wood and plant remains. Clays found on Resolution Guyot are characterized as chlorite, glauconite, hydromica, illite, kaolinite, saponite and smectite. Claystones have also been found. Most clays have been found in the lower carbonate sequence, while the upper parts mostly lack clay deposits. Some of the clays may originate from younger volcanoes east of Resolution Guyot. Apatite formed through phosphate modification of exposed rocks underwater. Other minerals include anhydrite, celestite, goethite, gypsum, limonite and pyrite which is also present in the carbonates. Finally, mudstones have been found. Geologic history Although radiometric dating has been carried out on volcanic rocks from Resolution Guyot, the basalts are heavily altered and the dates are thus uncertain. Potassium-argon dating yields ages of 107–125 million years ago while argon-argon dating indicates ages of 120–129 million years ago. Magnetization data indicate that it was formed in the Southern Hemisphere. Volcanic phase Eruptions in the area built