PREHISTORIC STRATIGRAPHY OF THE SOUFRIèRE HILLS-SOUTH SOUFRIèRE HILLS VOLCANIC COMPLEX, MONTSERRAT, WEST INDIES

Abstract

The Soufriere Hills and South Soufriere Hills volcanoes are morphologically distinct but petrologically similar. The history of the complex is subdivided into seven episodes. The Soufriere Hills subunit I (<= 175 ka) has deposits of Pelean style with ignimbrites of Plinian style abundant near its top. This is followed by deposits from the South Soufriere Hills (similar to 130 ka) that represent open-crater St. Vincent-style activity. Soufriere Hills subunits II-V (similar to 12,000-similar to 400 BP) return to more characteristic Pelean activity; at similar to 22,000 BP, block-and-ash flow deposits containing abundant clasts of vesicular andesite dominate. Age dating shows that renewed activity began just before European settlement in 1632 CE. This activity, including the ongoing eruption, is typical of the dominant eruptive style of this volcano for the last 175 ka.