Layered pyroclastic hydro – volcanic deposits of sub-parallel or cross-beded layers of angular lapilli and ash from perlitic aphyric pumice.
These create a common tuff ring, covering the lavas of Kamara. In the juvenile fragments, the few micro-phenocrysts are plagioclase, hornblende, clinopyroxene, biotite and magnetite.
Maximum thickness reaches 10 meters.